OF2likR MO. c:"iN~F`:3 flf='F'f20V(~L Of= WOktCStiOF' Ofd 'fl-IE' RfalfdWHTE:P. GOI_L.Ei=CTIC)fd IfdCENTIVE F'R06Rt-lht On tl-~i.s tl-~e c9th day crf May ~'.0V~1, upon mni;:ion made by Comru:iras:iiiner• Wi1li.ams, secarrded by Carnmis=...ior~t~r Let:, bhe Co~..rrt unanimously approved by a vote of 4-0-~, to si_tir:.dule ea vaorltst7r}F, orr 'L-tre Rtiir-~avater~ Collecti.or~ IrICF?Yit1.Ve Pr~oyre:~m fcrr Mnr~day, ,Ti.irre ;_'`~, ~'~~1 at ~ F'. M. in th're Kerr Coi_~nty Co~.irtho~_rse Ca~_u^troom. COMMISSIONERS' COURT AGENDA REQUEST PLEASE FURNISH ONE ORIGINAL AND NINE COPIES OF THIS REQUEST AND DOCUMENTS TO BE REVIEWED BY THE COURT. MADE BY: William H. Williams OFFICE: Commissioner, Pct. 2 MEETING DATE: May 29, 2001 TIME PREFERRED: SUBJECT: (Please be specific) Consider and discuss establishing a Kerr County Rainwater Collection Incentive Program that would provide a property tax exception for cost of purchase and installation of rainwater harvesting equipment; in conjunction, establish a Kerr County Linked Deposit Program, as added incentive, and set date for public workshop on same. EXECUTIVE SESSION REQUESTED: (PLEASE STATE REASON) NAME OF PERSON ADDRESSING THE COURT: Bill Williams, Commissioner, Precinct 2 ESTIMATED LENGTH OF PRESENTATION: 10 minutes. IF PERSONNEL MATTER NAME OF EMPLOYEE: Time for submitting this request for Court to assure that the matter is posted in accordance with Title 5, Chapter 551 and 552, Government Code, is as follows: Meeting scheduled for Mondays: 5:00 P.M. previous Tuesday THIS REQUEST RECEIVED BY: THIS REQUEST RECEIVED ON: All Agenda Requests will be screened by the County Judge's Office to determine if adequate information has been prepared for the Court's formal consideration and action at time of Court meetings. Your cooperation is appreciated and contributes toward your request being addressed at the earliest opportunity. See Agenda Request Rule adopted by Commissioners Court. KERR COUNTY RAINWATER HARVESTING PROGRAM BENEFITS AND QUALIFICATION CRITERIA PROGRAM HIGHLIGHTS • Up to One Hundred Dollar ($100) fee reimbursement for new development permitted in Ken County through UGRA and/or HUWCD. • Property tax reduction: Taxable value reduced by the rainwater collection system and construction costs. (To be established by Kerr Central Appraisal District). BENEFITS • Free high-quality water for your use, • Reduces groundwater demands, • Saves costs for water, electricity, water softener expenses • Reduces salt discharges into soil • Limits runoff while reducing storm water pollution • Fire protection • Peace of mind QUALIFICATION CRITERIA • Kerr County Application approval (through either UGRA or HUWCD • Minimum storage capacity: 2,500 gallons • Annual application and approval for tax exemption (which is required by state law) to be submitted to KCAD • Sunlight restrictive design to help prevent algae growth • Insect-proofing required PROPOSED PROGRAM ENHANCEMENTS • Seek amendment of Senate Bill One to expand water conservation initiatives by exempting from sales tax purchase of rainwater collection systems and/or installed products, if not accomplished in current session of state le¢islaturel. • Work to establish a Water Pollution Control Loan Fund (Linked Deposit Program). This could allow a lower interest rate (usually 2% below market) for loans financing rainwater collection systems. Rainwater Collection Incentive Program "Typical Savings" For a new system valued at $10,000. 1. Permit fee rebates (up to) 100. 2. $10,000 x $ /evaluation ???? 3. Savings from "Linked Deposit Frogram" a. 2% interest reduction on $10,000 five year note 565. Note: An unsuccessful attempt was made during the recently- concluded Texas legislative session to exempt from state and local sales tax the cost of a Rainwater Harvesting System. Counties that adopt Rainwater Harvesting Programs should consider seeking a sales tax exemption for this equipment from the next legislature. Proposal for Asset Evaluation of Rain Water Collection Systems Based on the following premises: 1. The value of the system is not the sum of its parts, but the value of the product, which is water. 2. Any piece of property with an available water supply is worth more because of that water supply. 3. A fihrated water supply for potable water is worth more than an unfiltered irrigation supply. 4. A minimum base should be set on qualifying system based on capacity due to the base cost of administering the tax credit, and the type of installations you wish to encourage. 5. The basic valuation system should be simple to calculate and sinular to ($??) per foot for construction, or $XX.XX dollars per foot ofrunning fence. Based on the above premises the following is suggested: 1. Unfiltered water catchment system over 2,500 gallon capacity to be valued at $1.50 per gallon of storage. (Note: check with aoaraisal district to determine suggested amounts for irrieation-only systems and notable water systems). Some have used $3000 to $5000 for irrigation-only systems, and $20.0110-25 000 for notable water systems depending on the comolexitv). 2. Figures for asset evaluation of filtered water catchment system over 2,500 gallon capacity, qualifying as potable water supply by inspection must also be established. To continue complete development of information, the following is suggested: • Review materials that may be available from Kerr Central Appraisal District. • Review preliminary figures with homeowners who have installed systems in Kerr County (or neighboring counties) and receive feedback on value figures. • Assess Kerr Central Appraisal District's method of assigning asset values to producing wells in our area. • Calculate "Payback" on investment in system based on current and projected water rntes. Example: Aquasouree water rates for 15,000 gallons of water are $ , or cents per gallon. * Figures also based on estimates of installed price, i.e., 3,000 gallon system for irrigation purposes might be assessed at $4,500 of added value to a property. xERR couNTY Site Address: Application for Rainwater Collection System Incentive Program Legal Property Description: Subdivision Lot Daytime telephone Construction start date Estimated completion date: Square footage of collection area: Block Total system storage capacity: Qallons Planned use: Potable_ Non-potable Distribution method: Gravity flow Pumped Disinfection: Yes_ No Method Do you authorize release of your address and system capacity for Fire Department mapping and emergency use? Yes No Additional Application Requirements: • Project summary • Site plan with detailed system design • Detailed cost estimate $ , (list capital outlays), or • Firm project bid: $ _ Completion Information Date of completion: Completion Verification: Requires signature of County or Central Appraisal District Official. KERR COUNTY Linked deposit program For Rainwater Collection Systems What is a Linked Deposit? The Linked Deposit program is a mechanism to provide financial incentives for any particulaz goal or purpose, in this case the financing of rainwater collection systems. Instead of borrowing directly from a county fund, a loan is made to the applicant by a local lending institution, The below-market rate of the loan is supported by a certificate of deposit, provided in this case by the county. The certificate of deposit does not guazantee or secure the loan; it does however reduce the interest rate of the loan. Linked Deposits have been used by a number of agencies to promote everything from job creation, small business, agriculture diversification, forestry and land management best practices and student loans. FLOW CHART FOR AWARDING DEPOSITS 1. A homeowner applies for a loan from one of the local azea lenders participating in the Kerr County Linked Deposit Program. 2. The local lending agency evaluates the credit-worthiness of the homeowner using its own criteria. If these criteria aze met, the local lender then enters into a loan agreement with the homeowner. 3. The local lender sends aone-page application form, which identifies the homeowner and terms of the loan to the county. Upon approval, the county deposits a certificate of deposit with the local lender, funds equal to the face value of the loan to the homeowner. The term of the deposit is equal to the term of the lender's loan with the homeowner. 4. The interest rate on the certificate of deposit is discounted below the lender's normal cost of funds, as determined by a comparison to the interest rate of U. S. Treasury notes and bonds. 5. The interest rate of the lender's loan to the homeowner is reduced by the same amount as the discount the lender received from the Ken• County LDP. ADVANTAGES OF THE PROGRAM 1. The Linked Deposit Program provides an economic incentive for homeowners to conserve water resources by installing rainwater collection systems 2. Homeowners would work with local lenders and not a county department. 3. The Linked Deposit is not a security for the homeowner's loan; therefore if there is default, the county will not incur a loss. 4. Participating lenders have the existing structure and experience to make and administer the loans. If this were not present, there would be an administrative expense on the part of the county to administer the loans. 5. Participating lenders earn the same amount of profit as they normally would on their other loans. In addition, the lenders that participate can offer this as an additional service to their established preferred customers. 6. The Ken County LDP Certificate of Deposit would be insured by the FDIC, and therefore secure. 7. The wire transfer of funds from the Kerr County LDP to the participating lender would normally occur 1 to 2 days after the request is received. There is very little delay in the awazd of funds from the lender to the homeowner. SUMMARY In this program, homeowners obtain loans from local lenders for below mazket rate to install rainwater collection systems, saving water resources for the community. Local lenders eam the same amount of profit as they normally would from any of their other loans. The county uses grant funds instead of tax revenues and does not make or administer the loans. Total grant funds increase slowly over time because they earn a minimal interest rate, while they aze linked to the homeowners loans. This program has proven successful in many states for a variety ofpurposes. The State of Texas has had a Linked Deposit program in the Texas Department of Agriculture since the 1980's. A Linked Deposit program can be used to provide financial incentive for any particular goal or purpose which the county deems beneficial to the larger community. LINKED DEPOSIT PROGRAM Resident Resident wants to install rainwater collection system on their property Resident obtains project approval from local lender, up to $20,000. Then files 1 page application with Kerr County for participation in Linked Deposit Program. Resident receives low interest loan from local lender (3 to 4 percent below current market rate). Local Lender Any local lender insured by FDIC that desires to participate in Rainwater Harvesting Equipment loans. Local lender makes loan to property owner for cost of system up to $20,000. Local lender reduces interest rate by 3 to 4 percent below market rate to property owner for Rainwater Harvesting System Local lender offsets reduced rate to customer through County's CD of an amount up to $20,000. Kerr County Kerr County establishes Linked Deposit Program for Rainwater Harvesting Program participants at local lending insitution(s). Ken County receives 1 page application from property owner who desires to participate in program. Upon notification from bank of approval, Kerr County places CD in lending institution (up to $20,000) and accepts a lower interest rate as an offset to interest break given property owner. Kerr County's fund balance continues to grow through receipt of minimum interest on CD's. Kerr County does not lose money, and CD is NOT considered security for Rainwater Harvesting equipment loan. Commissioner Bill Bumett sat inside his Central Texas home and listened to the pitter-patter of raindrops. And then, he got an idea. Many of Burnett's ancestors, who've ranched for the last 90 years, collected raindrops in cisterns. "They practiced this type of (water) conservation 50 years ago," Bumett said. "I'm not sure how we got away from it" Water collection and conservation have taken on added meaning in Hays, seeing as it is one of the fastest growing counties in one of the fastest growing regions in the state. "We're going to have some serious water quantity problems...and it's only going to get worse," he said. "Phis problem will call for creativity and innovation, Bumett added. - So as the raindrops continued to fall, the commissioner continued to think. Perhaps homeowners, if given a little incentive, would consider doing their part to make sure Hays County would not run .out of water. A Helpful Nudge Burnett took his "rainstorm brainstorm" a step further and worked with a citizens committee and county staff to develop a program that will hopefully encourage residents to become less dependent on groundwater. Last fall commissioners approved the Hays County Rainwater Collection Tax Incentive Program, which al- lows homwtvners to exempt the taxable value of[heir col- lection systems. According to [he Lower Colorado River Authority (LCRA), Hays is one of the only, if not the only, county in the country to offer [his type of program. "I'm kind of proud that it's the first of its kind in the state," Burnett said. Once participants complete an annual application, they are able to exempt the taxable value of their system from their property tax. Irt addition, new homeowners receive a $100 rebate to be applied to their septic tank permit fee. Burnet[ hopes future savings are on the horizon. He is endorsing legislation, to be sponsored by Texas State Sen. J.E. "Buster" Brown, which would exclude from sales tax those items purchased to support a rainwater collection system. The collection systems vary, depending on the use of the water collected. The program has a minimum wllec- tion storage capacity of 2,500 gallons. The average cost of a system is about $1Q,000, although more elaborate sys- tems wind cost beyond $30,000, Bumett said. Most of the rainwater is collected off of rooftops into large storage tanks. The water is then run through pipes and into homes for filtration. The program has been operational for about six months, and the county is continuing to take applications from those who have rainwater collection systems in place. Actually, Hays County already is on the forefront of rainwater capture, at least in the Lone Star State, accord- ing to Nora Mullarkey, senior water conservation special- ist with the LCRA. Prior [o the inception of the [ax incen- tive program, the county led and still leads the state in the number of collection systems. In fact, the county has a system of its own at the county extension office. Hays County will partner with [he LCRA and other entities to sponsor a workshop this spring in San Marcos to explain rainwater collection and the tax incentive program. woove ien to rignt: Dripping Springs Library filtration & disinfection; a colleRion system on the property of Sam Davis; Sunset Canyon Pattery; and a collection system on the property of Mike 7essaro. February 2001 21 SAN ANTONIO EXPRESS-NEws SATURDAY MAY 19, 2001 47r 1_~C~ 1~1 NF,tiVS $ECCION B Z ~ i r~ Seminar touts rain as `harvest' System owners say I they're happy with water supply. BY Room dtarenu FXPRESSNEWS STAFF WRRER SAN MARCOS - When San Marcos Police Officer Jeff Caldwell built his home outside San Marcos four years ago, he knew neighbors' wells did not produce a lot of water and the water they did PmnP was very para. He also knew that, with more and more growth in Hays County, well kveLs+lil9rlY'~uld. decline in Doming Y~s~ __ . _. :.. So instead of digging a "well, he did what more and more rural landowners are doing: He built a rainwater harvesting system to provide his family with a depend- able water supply 'Z am 100 percent sold. on the system," Caldwell said ThwsttaY at an everting seminar organized by the Lower Colorado River Author- ity "We have two kidsand a Yard and we don't skimp on water at ~„ FSrm fign'es on the %number of rainwater catchment .systems in the area are riot available, but sev- eral basin a systems. 11te cen simple ~ home gutter • .to wa- }~. p " ' a sys- tem like at- tendees 'd "session, which drew 125 area. residents to the San Ivlaiws Activity Center. Caldwell built a 320Psquarefoot harm. The rain that falls on the roof is channeled into two 10,000- gallon tanks. The water is circu- lated by a pump and treated with owne before being pumped to his house. Under normal conditio ' ~ it pm vides all the water his ~ e and yard need, although last year's drought he had,"~ spend $150 to have 2,000 g-a11tiY18'"'of water delivered to his home:`,."ii':1<,' The fast flush of,.water is di- verted away from the tanks, and leaves and debris are ~iLered out. The maintenape~-artt~cwrts to occa- sionally s a Sew leaves from the ;the filter twice a malmry+sure the owne ge 3~~uorltitlg. Ken H .. -`ntesident of the Systems iairtwa- ter~ran 'be as,' ble as a well in aylpu use a mailerate amout$~ ~waAa~c" More people build rainwater-harvesting~sy~Errts, but they worry about droughts, said Hari Krishna, senior conservation engineer with the Texas Water De- velopment Board. "The perception th not de pendable is nt," Krishna said "B t how dable are wells going to ~ in a ~~fl., A system like Cald mst more than drilling a "°but the quality of the water an ing aquifer levels in some, ~ make it a good choice ~ - ~~said. Margaret water that falls on he -lement her Bulverde 'ch goes dry during dro "I am very ha Y Sys- tem," she said. }reasure. The quality is so m than the groundwater. It' clear. It tastes better. Thee4 come out of the dishwaslle[t RESOLUTION OF KERR COUNTY COMMISSIONERS COURT ESTABLISHING A RAINWATER COLLECTION INCENTIVE PROGRAM WHEREAS the 2000 census reveals that Kerr County is among the more rapidly-Bowing rural counties in Texas and is witnessing ever-increasing challenges to its limited water supplies, and WHEREAS Kerr County Commissioners Court recognizes that rainwater collection can provide a valuable and meaningful positive impact on long-term water availability for all county residents, and WHEREAS rainwater collection offers many benefits to users including: Beat tasting drinking water; reduced goundwater demands; savings in cost for water, electricity, and water softener expenses; reduced salt discharges into the soil; limiting runoff while reducing storm water pollution; fve protection; and peace of mind, and WHEREAS Region J Planning Group has included rainwater collection in its master plan for water development and conservation throughout its Geo-region, and WHEREAS to promote rainwater collection, Kerr County Commissioners Court establishes the following criteria for its Rainwater Collection Incentive Progam; and WHEREAS Kerr County Commissioners Court cages all other Kerr County taxing entities to approve similar orders in recognition of universal concerns for protecting our natwal resources and quality of life, now THEREFORE BE IT RESOLVED and ordered that the Ken County Commissioners Court adopts the following Rainwater Collection Incentive Progam providing 1. Ken County Application approval process, 2. Establishment of a minimum storage capacity requirement of 2500 gallons, 3. Annual application and approval for tax exemption , 4. Sunlight restrictive design, 5. Insect-proof construction, 6. A $100 development fee rebate, 7. Property tax exemption equivalent to 100 percent of the value of the collection system as determined by the Ken Central Appraisal District, Adopted by KERB COUNTY COMMISSIONERS COURT This of 2001. Fred Henneke County Judge H. A. Buster Baldwin Commissioner, Pct. 1 Jonathan Letz Commissioner, Pct. 3 William H. Williams Commissioner, Pct. 2 Larry Griffin Commissioner, Pct. 4 RAINWATER F3ARVESTING - StTPPLIERS ! B SINESSES ARCSA MEMBERS ; THE CAPTURED: RAINWATER COMPANY BARLEY BI PFEIFFER ARCHITECTa DRi CURTIB GNUaa PETER L. PFEIFFER P.O. BOX 1960 1800 W. 8TH 6TRHET BLAwCD, TX 78806 AuanN, TX 76709 830/633-4334 812/478.6680 WATER PILTRATYON COMPANY TIMBER TANM6 AMERICA, LTD. ~'>PHILL9P MGCLAY M. JACK HALL 1206 fdELMAN 3T. P.O'. BOX 91493 '. MARIETTA., OH :46780 AUlTt N, TX..78709 ]4{X379-8983 6821301.0669.,: RAINWATER SYSTEMS NORTHWEST LDUia IANA COMMERCE CENTER JOHN GOAT6 KIPPY CLARKE 9203 3. LAMAR 7OBdMADI80N AVE. AuaTIN, TX 78704 MINOe:N, I..A 71:066 5:12/442-7841 3IBf377-1867 THE' CENTERipOR MAXIMUM POTfi NTIAL BUILDING SYSTEMS Pu wY PIBK :8604 FM 96H` AuaTIN, TX S f 21928-4766 3F YOU WISH TO JOIN ARC6A. PLEASE YISIT OUR WEBSITH. WWW.ARCSA~U3A.ORG/ARCSA.HTAt POR fNP' ORAfATTON ANDM HMB£R$~11P FORM. TWDB LIST OF RAINWATER HARVESTING PROVIDERS THE FOLLOWING I6 A LIST PROVIDED FOR INFORMATIONAL PURPOSES ONLY, ANO INCLUSION OF A FIRM ON THIS LIST IS NOT NECESSARILY AN EN DOg6EMENT OF THAT FIgM OR IT6 PRODUCTS BY TWDB. PLEASE NOTIFY TWDB CONSERVATION SECTION AT (512) 463-]95$ OF ANY UPDATES OR CNgNGE6 THAT MAY BE NEEDED IN THE FOLLOWING lI6T. CAPTURED RAINWATER COMPANY LC FARM Bi RANCH SERVICE SUPPLY COMPANY P.O. BOx 1380 P.O. BOx 10185 BLANCO, TX ]8606 $qN ANTONIO, TX 78210 (830) 833-4334 (BOO) 292-000] Sysfler, LsfaYafkly wsrdlefbs, haahellf Cosmh tasks, ~/ woskm, ~~ 1Wns rsypNas, rosfieg rsypks, Prlyefkyl6M Nd ~Ikal~aSr fmFS L HI F MANUFACTURING P.O. BOx 5]B BARREL CITY U$A HIGHWAY 290 EAST 8401 SOUTH 1ST STREET GIDDIN66, TX ]8942 AUSTIN, TX ]8]48 (800) 23]-8]91 (512) 282-1328 flkergkss radu R.rydaa ss-gaVoa dress '. LANDMAgK $TRUCTURE6, INC. BARLEY B PFEIFFER ARCHITECT6-PETER PFEIFFER 1685 HARMOND RO. 1800 WE6T 6TH STREET AU6TI N, TX ]B]O3 FT. WORTH, TX 761]] (512) 4]B-8580 (617) 439-8888 Oq (BOO) 888-6818 ~IU syfro^ defys, derige/keN~ rasehafss Elrrafedsroel faskf STEPHEN BELL LAND6CAPE B IRRIGATION I MIDESSA MEMBgANES- 6804 WAGON TRAIN RD. MIDE66A INDUBTRIgL VINYL COMPANY AUfiTINr TX ]6749 4809 WE6T 42ND 3T. (512) 899-868H DOES6A, TX 79784 WATER6PIR IT2000®HOTMAI L.COM (915) 530-3055 Dangly srfdlefiox, rysfess, sarslfefila '' PVC bkaklars JOHN DORN TANK BUILDING, INC. PgELOAD, INC. P.O. BOX ISO 5]IO LBJ FREEWAY, SUITE 140 VIDOfl, TX 7]BJO-0150 DgLLA6, TX ]5240 (409) 769-5128 (800) 845-3198 gl~fld, gdraehel~ roofed rooks, asaklyo/ f®11s Cwaero tasks RED EWALD, INC. P.O. Box 519 KARNES CITY, T% J8118 (800)242-3524 Dasga kstagafioa system- iiberykss rem/arsed snobs RAINWATER COLLECTION OVER TEXAE 210 THURMAN RD. SAN MARCOS, TX JB666 (800) 222-3614 oR (512) 353-4949 Rakwoter syslems, service, rrpp0es, masoltatioe, desgn WATER FILTRATION COMPANY 1205 GILMAN MARIETTA, OH 45J50 (6007 J33-6953 OR (J40) 3J3-6953 Root warbers, floafiog Mters, mae RAINWATER SPECIALTIES JESS REIGN-PRESIDENT PO Box 282 W IMBERLY, TX J88J8 (SI2)642-8003 DR (512)632-1 JJI CATCHINGRAIN 1 aAOL.COM Rakwarar rdlertias systems, dsfen design aal emndotlure ENVIRO JET INC. 409 ENTERPRISE DR. H EwITT, TX J6843 (800) 880-4659 oR (254) 886-8181 RAINWATER SYSTEMS JOHN GOAT6 3203 S. LAMAR AUSTIN, TX J8J04 (slz) a42-Jea1 AUSTIN PUMP $ SUPPLY 3803 TODD LANE AUSTIN, TX J8J44 (512)442-2348 roryerkyleee tadls, prwps HIGH PLAINS NURSURY-JOHN LAOO 5202 RIVER RD AMARILLO, TX J910B (806)383-1 JOS LAOMAN®ARN.NET Rakwoter km'resfmg design and wstaRafioo JOHN TYBON CONSTRUCTION Box 22459 SANTA FE, NM 8]502 (505) JSJ-2188 OUODEROWE®CYBERMEEA.COM Sys/em Design d lnsfa0afan Erosmn Caotrol3 Catrkment LONESTAR EXTERIORS ANO COLLECTION 9VSTEMS JOSH LOCKER AND TYLER COFFEY SB04 $W PARKWAY SUITE 2222 AusTIN, TX JBJ35 (5121891-6868 oR (5121832-0149 Rdnwaler karvesting rdlettian systems design and ksfdlalion TANK TOWN RIC NARO REIN ICNEN 2JJ0 Hwv 290 WEST DRIPPING 9PRING S, TX JBB2D 512/694-0861 W W W.RA1N WATERCOLLECTION.COM 'Rdnwater ColkAion for Ike Merbaniro0y tlmDeaged" book 6 rkko available (or sak. Cdlasion systems design kstalkfion and egoipmeat IO acres of maey dispkys. TE%AS METAL CISTERNS LLC BO1 LOOP 4, SOVTX BLDG F, UNIT I PO Box 844 BUDA, TX ]8610 (512)295-9930 Manularore Galvanized Metal Tanks wick potable wales coating Design and kstdl Rakwoter Colkrtion Systems. MATT BACHAROY BUILDING DESIGN ASSOCIATE MEMBER OF THE AMERICAN INSTITUTE OF ARCHITECTS P.O. BOx 2669 WIMBERLEY, TEXAS JBfiJ6 1 (512) 84J-0802 BACH914B@FLASH.NET UUGty grade rainwater rolkrtka system design roasultkq. derign/bdd serrke TIMBERTANK6 OF TE%A6 TOMMY ROBICHAUX PO Box 91493 AUSTIN, TX J8J09 1(512)301-0669 1(512)301-5632 1(600)483-1696 Manrlatrrer o/ Wooden Water Storage Tanks with fksDk Membrane Livers Iran y00Gol to 1 M Gal, tanks. WWW.TIMBERTAN KS.COM TEXAS RAINWATER HARVESTING TIMOTHY SALA2AR 4211 LUCKENBACK SAN ANTONIO, TX ]6251 1 (210182)-5616 1(210)286-)523 Polyatbeleae looks, grtters aed otker water rorrerring prodves. M altenr- sire wurce al water tbet deaeoses depeodoMe w Ibe Edwards RgrRa. W W W.T%RAIN WATERHARV ESTING.COM GOLDEN EAGLE LANDSCAPE COMPANY 613 STATE HIGHWAY 2J EAST ING RAM, TX JD02$ TX. LICENBEO IRRIGATOR: L100883J (830)36)-4144 (630) 36J-25JJ (FwX) E-MAI L: GOLOENCO@KTC.COM SEE WEBSITE FOR DESCRIPTION. WWW.GOLDEN EAGLELAN DSCAPE.COM N ~, c~i .~ V ... ~. F~O r .~ "~ ~i cd b .~ ai oA a~ b N a~ ~. h~ ~. ~ .~ ~ ~ `~ °~ ~ ~ ~ ~ ~ o o ~ ~ _~ F ~ ~ ~ ~ ~ ~ ~ ~ "3 ~, ~ U 9 .~ ~ ~ N cd ~ i~. ~ •• ~ o ~ g ~ ~° ° A o ~ ~' ~ ~ 'Zt t~ • ~ .U ~ G~ by Cj tr a, ' ~ ~ ~ `~ a a' ~ N •N ~ v~ `~ ~ ~~ s.. ~ ~ ~ ~ ~ y ~ ~ Q ~ ~' ~ o ~ ~ c~ V b4 ~ ~ ~ w ~ ~ ~ ~ ~ ~ :.. ~ y ~ w-i bA ~ ~ ~ 3 ~ ° o° a~ ~ ~ o ~ c a~ ° ~ ,, ~ ' ~ " 'C3 N '~ .~ T3 • ^" '° .~ ~ ~ d N ~~ ~," ~ y N Cl ~ '~ . ~ ~ ~ __ .. " ~ ~ ~ ~ O ~ c¢ bA bA ' ~ ~ ~ ~ .~ ~ 3 ~ ,a? o 0 .'.~ cG .c ~ o ~ 3 ~ cis ~ v as ~ O Q .~ 0 bQ O O 0 a~ ... a~ x 0 0 0 O O O O M M N o, 0 N O a 0 C o fl, .. a~ 3 .~ 0 0 ~. a~ What is 1 inch of water? Experts tell us one inch of water a week is generally recommended for maintaining a viable landscape including vegetables, turf, trees and flowers. But exactly, what is 1 inch of water? The following conversions help make this cleaz. 1 inch of water from rainfall or applied from other sources • On 1,000 square feet = 624 gallons or 5,200 pounds • On 1 acre = 27,200 gallons or 200,000 pounds • On 1 squaze mile = 17.4 million gallons or 145 million pounds 1 gallon equals • 128 fluid ounces, 8.337 pounds, 3.782 kilograms • 15,100 drops, 16 cups, 8 pints, 4 quarts • 231 cubic inches, 0.2337 cubic feet • 0.83262 British or Imperial gallon • 3,785.4 milliliters or cubic centimeters • 1 cubic foot equals 7.48 gallons, 62.4 pounds • 1 cubic yazd equals 202 gallons, 1,685 pounds, 764.5 liters. • 1 cubic meter equals 264.2 gallons, 2002 pounds • 1 acre foot (12-inch depth across 43,560 squaze feet) equals 325,851 gallons, 2.7 million pounds. All good reasons to practice rainwater harvesting whenever and wherever possible. Riverside Nature Center Assn. P.O. Box 293970, )5o Lemos • Kerrville, Texas J8029 (830) 257-4837 We6site: www.ktc.net/riverside E-maid: rncaC9~ktc.com RNCA Ls a 501(c)(3) non-profit organization. Deaz Bill, The rainwater catchment system at Riverside is working very well, in fact we have been overflowing our 3000 gal tank for a couple of months now. Janet Robinson asked me to give you an idea ofthe cost involved in setting up a system. The figure of $1/gallon is fairly accurate except in our case where I did all the labor. Our basic cost was $1750 for 3000 gallons. The variables beside materials aze: Labor Gutters- (if not in place) Commercial Washers Filters Chlorinators(ifused aspotable water) Riverside's cost of materials was: Tank 3000 gallons $1100 Roof Washer 50 Piping, valves, fittings 2p0 Pump I50 Electrical 100 Foundation 100 Hose 50 Total basic cost $1750 The foundation can be concrete, wood or sand. We used sand, about 5 inches deep, smoothed level for the tank bottom it sit on. The normal calculation for yield is 600 gallons per 1000 squaze feet for one inch of rain. The square foot is the footprint of the building not the square feet of the roof. I would be happy to discuss this with you and answer any questions you might have. I have enclosed a sketch of our system. Sinc , Zit z./ April 2, 2001 QurrEe 4 "PIPE RooP~ 714N K ouTCET Pcu~s Pumv TY.nic.ac tv~ 7E~ e.¢ ~z'.~~~.~' AMERICAN RAINWATER CATCHMENT SYSTEMS ASSOCIATION (ARCSA) www.aresa-usa. org/aresa.htm ARCSA was founded in 1994 in Austin, Texas to promote rainwater catchment systems in the United States. Membership consists of professionals working in city, state, and federal government, academia, manufacturers and suppliers of rainwater harvesting equipment, consultants, and other interested individuals. The objectives of ARCSA are as follows: 1. To promote rainwater catchment systems through meetings and seminars, 2. To provide networking between people with experience in rainwater catchment systems and those who might need assistance in developing such systems, 3. To provide a fonim for discussion of new methods, techniques, and materials pertaining to rainwater catchment systems, 4. To develop informal publications to assist in the design and use of rainwater catchment systems, and 5. To establish acceptable treatment methods for harvested rainwater. ARCSA publishes a newsletter to keep members informed of developments in this growing field. ARCSA publications and events are free or discounted to members. Membership is open to anyone interested in rainwater catchment systems. We invite you to join ARCSA by filling out the attached membership form. Thank you for your interest. Dr. Hari Krishna, P.E., President Mr. Ken Heroy, P.E., Vice President Ms. Patsy Waters, Secretary/Treasurer Mr. Max Castaneda, WebMaster ARCSA Newsletter American Rainwater Catchment Systems Association www.arc Welcome to New and Renewing Members: Dr. P.E. Besant-Matthews -Dallas, TX Sean Twomey -Ottawa, Ontario, CANADA Margaret Ruth Baker - Bulverde, TX Jeanne Erickson -Richland Hills, TX Northwest Louisiana Commerce Ctr -Minden, LA Hugh "Bud" Kane -Austin, TX Osvaldo Valdez -Yorktown, TX Richard Williams -Mill Valley, CA Will Ed Winters - Spicewood, TX Ken Heroy -Austin, TX Richard Peterson -Austin, TX Texas Water Development Board -Austin, TX Rainwater Systems -Austin, TX Barley 8 Pfeiffer Architects -Austin, TX Timber Tanks America; Ltd. -Austin, TX Water Filtration Company -Marietta, OH Center For Maximum Potential Building Systems- Austin, TX The Following Continue as Life Members: Dr. Hari Krishna -Austin, TX Or. Dennis Lye -Taylor Mill, KY Dr. Ashok Reddy -Austin, TX Professor Yu~Si Fok - Honolulu, HI Bowefiird Construction -Dripping Springs, TX ARCSA OFF/CERS Dr. Hari Krlshna, P.E., President Mr. Ken Heroy, P.E., Vice-President Ms. Palsy Waters, Secretary?reasurer Mr. Max Castaneda, Wehmaster Rainwater Catchment Systems Conference An Intemational Conference on Rainwater Catchment Systems will be held in Mannheim, Germany from Sept. 10-14, 2001. The conference will be held in conjundion with the Intemational Rainwater Fair, where more than 100 exhibitors are expeded to partidpate. The conference is being organized by IRCSA, the International Rainwater Catchment Systems Association FAKT, a European non-profit consultancy oranization, and fbr, a German non-profd professional association. More information on the conference may be obtained at www. ra inwaterconfe rence. ora .htm Rainwater Harvesting Seminar 8 Tour ARCSA Is co-sponsoring a Rainwater Harvesting (RWH) Seminar/Workshop, followed by a Tour of RWH sites on Thursday, May 17, 2001. The event is being sponsored by several agendes induding the Lower Colorado River Authority (LCRA), Hays County, Texas Water Development Board (TWDB), Pedernales Eledric Cooperative (PEC), and the Edwards Aquifer Authority (EAA). The workshop will be held at the San Marcos AdivRy Center, San Marcos, Texas on May 17, 2001 from 9:00 am - 1:00 P.M., followed by lunch, and a RWH field tour thereafter. Pre-registration is required, there is no fee for attending, and lunch is included. Several speakers are being centaded for talks and panel discussions. ARCSA Members: Please treat this as an invitation to attend. More information will be available on this event from Ms. Patsy Waters at (512) 463-7955 after April 15, 2001. Rebates, Tax Incentives and Exemptions The City of Austin provides rebates for Rainwater Harvesting. By conserving water, there are several advantages for a Utility, such as: * Redudng the demand for treated drinking water, * Postponing censtrudion of new water treatment plants or delaying the expansion of current plants, * Redudion in energy needed for water treatment, pumpage and distribution, and * Creation of a new and localized water supply at minimal cost The Cily of Austin provides rebates of up to $500 to residential and commerdal water customers for newly installed rainwater harvesting systems. Applications must be approved before equipment is purchased. More information and assistance are available by calling the water conservation sedion at the City of Austin, (512) 499-2199. See Rebates.... Next page Rebates..... Hays County in Central Texas has become the first county in the nation to provide tax incentives for rainwater harvesting. The county, as part of the Rainwater Colledion Incentive Program, provides a $100.00 development fee rebate and a property tax exemption equivalent to 100 percent of the value of the rainwater Colledion system. Wdh mounting concern over depleting groundwater supplies, and due to the marginal quality of groundwater in many situations, rainwater harvesting is becoming a valuable aHemate technique for increasing water supplies. Other counties in the region are also exploring such tax incentives and programs to promote rainwater harvesting. In addition to the efforts by cities and counties to encourage rainwater harvesting, The Texas Legislature is currently considedng a bill to promote water conservation in the State. The Bill (Senate Bill 1332 and accompanying House Bill 2402) 'rf passed, will provide among other things, sales tax exemptions for items to be purchased and used for rainwater harvesting. This should go a long way in promoting rainwater harvesting in Texas. The Arizona Department of Water Resources (ADWR) has published a guide entitled 'Harvesting Rainwater for Landscape use°. It was prepared by Pima County Cooperative F~dension in cooperation with ADWR and the University of Arizona Water Resources Research Center. ARCSA 13149 Bayfield Drive Austin, TX 78727 Rainwater Harvesting Guides The Texas Water Development Board has published an excellent guide on Rainwater Harvesting, in cooperation with the Center for Maximum Potential Building Systems. It is entitled "Texas Guide to Rainwater Harvesting", and has a considerable amount of information useful to any prospedive user of such systems. In order to promote rainwater harvesting, the Texas Water Development Board (TWDB) is making this publication available to anyone free of charge, on the world wide web. This free guide can be downloaded from the TWDB website: www.twdb.state.tx.us . Alternatively, log on to the ARCSA website www.aresa-usaorrJaresa.htm and click on the link to the RWH Guide. The City of Albuquerque, New Mexico has just published a guide 'Rainwater Harvesting: Supply from the sky'. The publication covers various components of a RWH system and the amount of water to be colleded at various locations in the State, but primarily deals with rainwater harvesting for landscape use. Albuquerque residents may order this publication from the CRy's Water Conservation Office at (505) 768- 3655. Others are asked to contad the Office of the State Engineer, Water Use and Conservation Bureau, P.O. Box 25102, Santa Fe, NM 87504-5102. ADDRESS CORRECTION REQUESTED AMERICAN RAINWATER CATCHMENT SYSTEMS ASSOCIATION (ARCSA) www.aresa-usa.org/aresa.htm Membership: Initial Application OR Renewal Date: Name: Address: Fax: Please circle one or more of the following that may apply to you: 1. Rainwater harvesting systems manufacturer or supplier 2. Current or Prospective user of rainwater harvesting systems 3. City /State /Federal Govt. Employee /Scientist /Engineer 4. Other (Please specify) Membership dues (Please check one, below): ANNUAL DUES: Individual: $ 20.00 Business/Org: $ 50.00 LIFE MEMBERSHIP: Individual: $ 100.00 Business/Org: $ 250.00 Please make your check payable to ARCSA and enclose with this form, thank you. Mailing Address: ARCSA C/o Dr. H. Krishna 13149 Bayfield Drive Austin, Texas 78727 ' COMP~Uf ENTS UGRA TEXAS GUIDE TO Texas Water Development Board in Cooperation with the Center for Maximum Potential Building Systems Second Edition 1997 AUSTIN, TEXAS Texas Guide to Rainwater Harvesting SECOND EDITION ACKNOWLEDGMENTS This is the secotrd edifier of this publication. Tn this edition, the staff of the Texas Water Development Board have added several significant new pieces of information and have modified others as mote informadon become'; available in this rapidly changing field. This has resulted b'r a tent which differs somewhat firm the anginal text written by the Center for Maximtun Potential Building Systett>s. As new infornadon becomes available, the Board staffwlll make appropriate cianges in future addidors as time and funds permit. Tn addition to the recognition of contributors presented in the original acknowledgment below, the Texas Water Development Board staff would like to recogrrirs Matthew Badanly, Harley and Pam Rose, Peter Pfeiffer, Kate Houser, Duncan Echelson, Jeff Reich, and others who helped conhibute to the second edition's tedudta) content. ORIGINAL ACKNOWLEDGMENTS The Texas Crride m RafrnsemrHarvsstingwas developed by the Center fa Maximum Potential Building Systems. Austin. Texas, trader the direcdon ti'Gail Vittod, with funds pttrvlded by the Texas Water Development Board Contract595-483-136. The Guidewas researched and written by Wendy Price Todd, ACA and Gail Vittod, and edited by BID Hoffman, P.E., Kerr Hoy and Janie Hopkins. Graphic design and producder was provided by Worldwise Design Creative Director I-Iazrlson Saunders Spanish translation by Cristlna Villarreal. The Center far Maximum Potential Building Systems, established in 1975 and based th Austn, Texas, is a norr-pnBt eduotlet, research, and denwnshation organi~tlon dedicated to sustainable planting, design and deve]opm~rt. For more information on the Center's adivlttes, contact us at 8604 F.M. 969, Austin, TX 78724, 512-926-4786. The authors would like to Clank the following agencies and individuals for their valuable assistance: Laurence Doxsey, City of Austn Green Builder Ptngram; Mania Roberts, Lower Colorado River Authority, Mike McElveen; Mary Sanger, Texas Center for Policy Studies; Hugo Gardea, Texas Histeical Commissier; Ron Bearden and Wends White, Texas Natural Resource Ctxrsetvation Commission; Dennis J. Lye, U.S. EmironrnerrW Protection Agency, Yu-$i Fok, University of Hawau; Phillip S. McClay, Water Filtration Company. Jce Henderson, Water Quality Association; the contractors fisted in the Resource section; and the participants in the Case Studies. Texas Guide to Rainxat~ Harvesting CONTENTS IS RANYWATER HARVESTING FOR YOU? ................................... 1 IUTRODUCTION ..................................................................... ll I. THE WATER CYCLE ............................................................ 1 11. ADVANTAGES OF RAINWATER .........:.................................... Environmental Advantages ................................................................. Qualitative Advantages ....................................................................... III. WATER QUALITY CONSIDERATIONS ........................................ Primary Water Quality Criteria -Health Concerns ........................ Secondary Water Quality Criteria -Aesthetic Concems ................ IV. HOW DOES A RAINWATER HARVESTING SYSTEM WORK? ............ 6 System Components ............................................................................. 6 A. Catchment Area .............................................................................. 6 B. Gutters and Downspouts (with Screens and RaoRvashers) ............. 7 C. Storage Tanks .................................................................................. 9 D. Conveying ....................................................................................... IZ E. Water Treatment (Filters andDisinfection) .................................... 13 V. HOW MUCN WATER DO YOU USE? ......................................... 16 Household Water Budget .................................................................... 17 Landscape Water Budget ..................................................................... 18 Water Conservation Techniques ......................................................... 18 VI. NOW MUCH WATER CAN YOU COLLECT? ................................. 22 Rainfall Date for Selected Communities Across Texas ................... 27 VII.COST CONSIDERATIONS ...................................................... 33 VIII.CODE AND SAFETY ISSUES ................................................. 35 IX. CASE STUDIES ................................................................. 36 Masonry and Contrete ........................................................................... 36 Masonry .................................................................................................. 36 Cast in Place Concrete ............................................................................ 37 Gunnite ................................................................................................... 38 Fetrocement ............................................................................................ 38 P1asHc .................................................................................................... 42 Fiberglass ................................................................................................ 42 Polyethylene ........................................................................................... 47 Metal .................................................................................................... 48 Steel .................................................................................................... 48 Composite Systems ................................................................................ 51 Composite ............................................................................................... 51 In Process ................................................................................................ 53 XI. APPENDIX ....................................................................... 54 Glossary .................................................................................................. 54 Abbreviations ........................................................................................ 55 References .............................................................................................. 55 = Texas Guide to lZatnwater Harvesting IS RAINWATER HARVESTING FOR YOU? he Texas Guide to Rainwater Harvesting is a primer of the basic prinaples of captured rainfall, with an emphasis on residential and small-scale commercial applications. If you are considering rainwater harvesting as a partial or total source of your water supply for new construction or remodel- ing, this Guide and accompanying videotape pro- vide the essential information to enable you to design a system that meets your needs. Most Texans have not had to operate their own water system. Your utility has done that for you. If you plan to use a rainwater harvesting system for your source of drinking water and for other direct human purposes, you must be willing to make a commitment to its long term, proper operation and maintenance, or you could endan- ger your family's and friends' health. Your local health department and city building code of- ficer should also be consulted concerning safe, sanitary operations and construction of these systems. As you read this manual, seriously consider what you want your system to do and how you will provide back-up water if you are designing the system as a supplemental water source, or in the event of severe drought. The case studies, covering several dozen installations operating in Texas, provide an excellent snapshot of current systems. What makes rainwater harvesting the pre- ferred water source -for some Texans today? While large, sophisticated systems are not cheap, some Texans have devised innovative approaches that are both effective and afford- able. Rainwater catchment systems provide a source of soft, high quality water, reduce reli- ance on wells and other water sources, and, in many contexts, are cost-effective. Systems can range in size from a simple rain barrel to a contractor designed and built system costing thousands of dollars. However, rainwater har- vesting systems are inherently simple in form, and can often be assembled with readily avail- able materials by owner-builders with a basic understanding of plumbing and construction skills. If you plan to use the water for human consumption, it is wise to consult or employ experts. Texans with the time and the inclina- tion to build their own system .can save a significant portion of costs associated with la- bor. Regardless of whether you intend to hire a contractor or build a system yourself, we rec- ommend that you read through the entire manual before starting a catchment system of your own. 1 Texas Guide ro Rainwater Harvestlng y INTRODUCTION or centuries in Texas and throughout the world, people have relied on rainwater har- vesting tosupply water for household, land- scape, livestock, and agricultural uses. Be- fore large, centralized water supply systems were developed, rainwater was collected from a variety of surfaces-most commonly roofs-and stored on site in tanks known as dstems. With the advent of large, reliable community treatment and distribu- tion systems and more affordable well drilling equipment, rain harvesting systems have been all but forgotten, even though they offer a source of pure, soft, low soditun water. Arenewed interest in this time-honored approach has emerged in Texas and elsewhere due to: ^ the escalating environmental and economic costs of providing water by centralized water systems or by well drilling; ^ health concerns regarding the source and treat- ment of polluted waters; ^ a perceptlon that there are cost effidendes assod- ated with reliance on rainwater. From mck dsterns to hollowed out tree trunks, historical precedents abound that trace people's reliance on rainwater collection. The Hueco Tanks in west Texas are natural rock basins that trapped rainwater for the native dwellers, from the archaic hunters to the Mescalero Apaches, and later be- came astopping point for stagecoach travelers. In south Texas and the Rio Grande Valley, central plazas were often not only the place where the townspeople congregated for soda] affairs, but also were the collection surfaces for vast under- ground tanks that collected and stored water for use by adjacent shops and homes. Such notable historic structures as the Stillman House in Brownsville, the Fulton Mansion near Rockport, the Freeman Planta- tion neaz Palestine and the Carrington-Couvert House in Austin collected rain from their roofs, and then guttered and piped the water into an above- ground tank or cellaz dstern. While many of these systems are no longer in use, they signify the impor- tance that early Texas settlers placed on captured rainfall for sustenance. Today, island states such as Hawaii and entire conti- nents such as Australia promote rainwater harvesting as the prindpal means of supplying house- hold water. In Bermuda, the U.S. Virgin Islands and other Caribbean islands where rainwater is the most viable water supply option, public buildings, private houses, and resorts collect and store rainwater. And in Hong Kong, skyscrapers collect and store rainwater to supply the buildings' water regtrirements. As with other natural systems. rainfall maintains its own cycles and patterns as evidenced by the severe droughts that devastated the Texas landscape in the 1950's, as well as the floods of 1981 and 1993 that ravaged east, south, and central Texas. These extremes underscore the importance of designing your rainwater catchment system with a thorough understanding of the basic prindples and essential information contained in this Guide. As you will see in the following pages, many Texans today ate putting their dollars behind alife-long invest- ment in a rainwater harvesting system over other options. A dedsion to reduce household water con- sumptlon to live within your means is a commitment that may not be for everyone, but it may be for you. ii Texas Cuide ro Rainwate Harwstlng WEST ELEVATION J EAST ELEVATION THE CARRINGTON-COUVERT HOUSE (1857) Colorado S[reet, Aus[in, Texas Colorado Street C North - 16th Street iii ROOF PLAN Texas Culde to Rainwater Harvesting I. THE WATER CYCLE henever-ending exchange of water from the atmosphere to the oceans and back again is known as the hydrologic cycle. This cycle is the source of all forms of precipitation (hail, rain, sleet, and snow), and thus of all water Precipitation stored in streams, lakes, and soil evaporates while water stored in plants transpires to form clouds which store the water in the atmosphere. RECHARGE / / ~ / / / / / 1 ~'.• BUT NOT SATURATED :~. ~':: ~.. ~...1 ~+ PERMEABLE ROCK± ~' CONTAINING FRESH GROUNDWATER (WATER TABLE) Currently, about 75% to 80% of conventional water supplies from lakes, rivers, and wells are developed and in use in Texas. Making the most effiaent use of our State's limited and precious resources is essential. This includes using appli- ances and plumbing fixtures that conserve water, not wasting water, and taking advantage of alter- native water sources such as greywater reuse and rainwater harvesting. r r~ WATERVAPORTRANSPORi OCEAN TOOCEANAND OCEANTO LAND RUNOFFIN }(~ STREAMS (( (1 • ~ _ EVAPORATION ~t'~ ~ • ' " ANOTRANSPIRATION ~:'7 - ~ BY PLANTS ~. ~•:'~ .. .aL' r~ t. ' ~. ~? ."• V e 1 EVAPORATION FROM OCEAN ~~~ . DDFAN AdvantagesntRainwater II. ADVANTAGES OF RAINWATER or some Texans, rainwater's environmental advantages and purity over other water op- tionsmake it their [op choice, even with their knowledge that precipitation cycles can fluc- tuate from year to year. ENVIRDNMENTAL ADVANTAGES Collecting the rain that falls on a building to be used neazby is a simple concept. Since the rain you harvest is independent of any centralized system, you are promoting self-sufficiency and helping to foster an appreciation for this essential and precious resource. Collecting rainwater is not only water conserving, it is also energy conserving since the energy input required to operate a centralized water system designed to treat and pump water over a vast service area is bypassed. Rainwater harvesting also lessens local erosion and flooding caused by runoff from impervious cover such as pavement and roofs, as some rain is instead captured and stored. Thus, stormwater tun-off, the normal conse- quence ofrainfall which picks up contaminants and degrades our waterways, becomes captured rainfall which can then fulfill a number of productive uses. Policymakers may wish to reconsider present as- sumptions regarding impervious cover and conse- quent nm-off management strategies when rainwa- ter harvesting systems are installed. QUALITATIVE ADVANTAGES A compelling advantage of rainwater over other water sources is that it is one of the purest sources of water available. Indeed, the quality of rainwater is an overriding incentive for people to choose rainwater as their primary water source, or for specific uses such as watering houseplants and gardens. Rainwater quality almost always exceeds that of ground or surface waters: it does not come into contact with soil and rocks where it dissolves salts and minerals, and it is not subject to many of the pollutants that ofen are discharged into surface waters such as rivets, and which can contaminate groundwater. However, rainwater quality can be influenced by where it falls, since localized indus- trial emissions affect its purity. Thus, rainwater falling innon-industrialized areas can be superior to that in aties dominated by heavy industry, or in agricultural regions where crop dusting is preva- lent. Rainwater is soft and can significantly reduce the quantity of detergents and soaps needed for clean- ing, as compared to typical municipal tap water. Additionally, soap scum and hardness deposits disappear, and the need for a water sofrener, often an expensive requirement for well water systems, is eliminated. Water heaters and pipes will be free of deposits caused by hard water and should last longer. Rainwater's purity also makes it an attrac- tive water source for certain industries for which pure water is a requirement Thus, industries such as rnmputer microchip manufacturing and photo- graphic processing may also wish to examine this source of water. 2 Texas Guide to Rainwater Harvesting III. WATER QUALITY CONSIDERATIONS eople who relied on rainwater systems 30 to 40 years ago may well reca1J contamination as a serious concern. Because the construc- tion methods and materials used to build many of the rural cisterns were not in compliance with today's standards, and bemuse of inadequate treat- ment procedures, illnesses associated with drinking unheaJthlul water were not uncommon. However, rainwater can provide rJean, safe, and reliable water so long as the collection systems are properly built and maintained, and the water is treated appropriately for intended uses. PRIMARY WATER QUALITY CRITERIA - HEALTH CONCERNS Once rain comes in contact with a roof or collection surface, it can wash many types of bacteria, molds, algae, protozoa and other contaminants into the ANNUAL PARTICULATE MATTER (PMt~ EMISSIONS IN TEXAS BY COUNTY, 1894 cistern or storage tank. Indeed, some samples of harvested rainwater have shown detectable levels of these contaminants. Health concerns related to bacteria, such as salmonella, a-coli and ]egionella, and to physical contaminants, such as pesticides, lead, and arsenic, are the primary criteria for drink- ing water quality analysis. Falling rain is free of most of these hazaids. Common sense takes a lot of the guess work out of proper treatment procedures. For example, if the rainwater is intended for use inside the household, either for potable uses such as drinking and cooking or for non-potable uses including showering and toilet flushing, appropri- ate filtration and disinfection practices should be employed. If the rainwater is to be used outside for landscape irrigation, where human consumption of the untreated water is less likely, the presence of ^ Less than 70 tans per year ^ 10 to t00lons per year ® 700 [o SOO rata per year 500 to 1,000 torn per year More Uun 7,000 tans per year ~ Less than 70 tans per year ~{ ®^ 10 to too fora per year L"~p1 100 to 500 tons per year .500 to 1,0001ore per year ~ More than 7,000 bra per year Source:- Texas Natural Resource Canservatlon Cmnmisslon ANNUAL SULFUR DIOXIDE (S0~ EMISSIONS IN TEXAS BY COUNTY, 1894 Water Quality Consideratlons contaminants may not be of major concern and thus treatment requirements can be less stringent or not requited at all. Depending on where the system is located, the quality of rainwater itself can vary, reflecting expo- sure to air pollution caused by industries such as cement kilns, gravel quarries, crop dusting, and a high concentration of automobile emissions. SECONDARY WATER QUALITY CRITERIA - AESTHETIC CONCERNS Aesthetic concerns such as color, taste, smell, and hardness comprise the secondary testing criteria used to evaluate publicly supplied water When assessed according to these characteristics, rain- water proves to be of better quality than well or municipal tap water Inorganic impurities such as suspended particles of sand, clay, and silt contribute to the water's color, and smell. Proper screening and removal of sedimentation help to decrease problems caused by these impurities. Rainwater is the sofrest natural occurring water available, with a hardness of zero for all practical purposes. In central and west Texas, dust derived from limestone and alkaline soils can add as much as one or two milligrams per liter (mg/L) of hard- ness to the water, although these amounts are negli- gible compared to the average hardness (about 200 to 400 mg/L) of groundwater in some areas. As mentioned above, a benefit of the soft water is that faucets and water heaters last longer without the build-up of mineral deposits. Rainwater contains almost no dissolved minerals and salts and is near distilled water quality Total dissolved minerals and salts levels average about 10 milligrams per liter (mg/L) across Texas. Total Dissolved Solids (TDS) can range as high as 50 mg/L and as low as 2.0 mg/L. These values are very low when compared to tity tap water across Texas, which typically is in the Z00 to 600 mg/L range, making rainwater virtually sodium free. For people on restricted salt diets, this represents a decisive advantage over other water sources. The pH of rainfall would be 7.0 if there were nothing else in the air. However, as rain falls through the air, it dissolves carbon dioxide that is naturally present in the air and becomes slightly aadic. The resultant pH is 5.6; however, any sulfates or nitrates dissolved from the air will lower this number below pH 5.6. According to National Atmo- spheric Deposition Program data, the pH of rainfall in Texas ranges from 4.6 in east Texas to 5.6 or above WATER QUALITY PROPERTIES RELATED TO SPECIFIC USES DOMESTIC INDUSTRIAL IRRIGATION Taste pH Boren Odor Acidity AlkallNty Poisons Alkalinity Sodium-Ca]Uum Ratio Flouride Silica Dissolved solids Nitrate Hardness Iron Sediment Hardness Dissolved solids Sediment Dissolved solids s _ - ! ~j = _--~ _ 4 Texas Guide to Rainwater Harvesting in west Texas. While northeast Texas experiences an even lower pH than found in other parts of the state, acid rain is still not Lronsidered a serious concern throughout Texas. Although the pH of rain is below neutral, it is only slightly aadic, and the smallest amount of buffering can neutralize the acid. The low total dissolved salts and minerals levels found in rainwa- ter permit even very small amounts of something like baking soda (one level tablespoon per 100 gallons) to adjust the pH to near neutral. The Texas Natural Resource Conservation Commission (TNRCC) monitors municipal water quality and has adopted Drinking Water Standards in accordance with the Federal Safe Drinking Water Act If you plan to use your harvested rainfall for drinking water, have the water tested by a labora- tory certified by the Texas Departrnent of Health (TDk-I) or Environmental Protection AgenLy (EPA). A list of drinking water testing criteria can be obtained from TNRCC or TDH. The Texas De- parhnent of Health performs tests for mliform bac- teria for a nominal fee at locations around the state. At least 100 mL of water are required to perform the test; results are available within five days. PH SCALE FROM BASIC TO ACID pH is the measure of aodity or alkalinity. In a scale from 0 to 14, 7 is neutral, values less than 7 repmsent more aad conditloru, values greater than 7 represent more Basic or alkaline conditions. The determinatlon of whether water is aatlic, neutral, or basic, is rrfemd to ~s pH, which is a measure of the hydrogen ion concentration in water. The tiesired pH of potable water is pH 7, while the scale ranges from values ofless than pH 7 down to pH 1 as increasinglyarrdic and greater than pH 7 up to pH 14 as increasingly basic Soda pop and vinegar have a pH of about 3.0. Rainwater Juice Diuilled Water Lemon JUice ~ \ Milk Blood gating Sotla Boras Ammonia T MiR of~ Magnesia Acid \ Vinegar \ \ \ I I SeaTWater T Corn Bleach 10 0 1 1 l 1 4~ 1 ,' ~ 12 j¢ \ 1~EUr ~ / / / MORE gCiD ~~ MORE BASiG -~p H S rC A L E._ 5 How Does a Rainwater Haryrsting System Work? IV. HOW DOES A RAINWATER HARVESTING SYSTEM WORK? SYSTEM COMPONENTS Whether the system you are planning is large or small. all rainwater harvesting systems are com- prised of six basic components: A. Catchment Area/Roof, the surface upon which the rain falls; B. Gutters and Downspouts, the transport chan- nels from catchment surface to storage; C. Leaf Screens and Roofwashers, the systems that remove contaminants and debris; D. Cisterns or Storage Tanks, where collected rain- water is stored; E. Conveying, the delivery system for the treated rainwater, either by gravity or pump; and F. Water Treatment, filters and equipment, and additives to settle, filter, and disinfect. A. CATCHMENT AREA The ratchment area is the surface on which the rain that will be collected falls. While this Guide focuses on roofs as catchment areas, channeled gullies along driveways or swales in yards can also serve as catchment areas, collecting and then directing the rain to a french drain or bermed detention area. Rainwater harvested from catchment surfaces along the ground, because of the increased risk of contamination, should only be used for lawn wa- tering. For in-home use, the roofs of buildings aze the primary catchment areas, which, in Waal set- tings, can include outbuildings such as barns and sheds. A "rainbarn" is a term describing anopen- sided shed designed with a large roof area for catchment, with the cisterns placed inside along with other farm implements. RAINWATER HARVESTING SYSTEM MAIM COMPONENTS ' ~ ~ ' ® Catchmem Rrea/ROOI i ~~ O O ~ Gagers arrtl ' ® Downspouts _ of f r ~ '~~ Cameyirg arN Water Trealmenl Storage TaN~ 6 Texas GWde to Rainxater Harvestlng Rainwater yield varies with the size and texture of the catchment area A smoother, cleaner, and more impervious roofimg material contributes to better water quality and greater quantty. While loss is negligible for pitched metal roofs, concrete or asphalt roofs average just less than 10°.61oss, and built up tar and grave] roofs average a maximum of 15°~ loss. Losses can also occur in the gutter; and in storage. Regardless of roofing material, many designers assume up to a 25%loss on annual rainfall. These losses are due to several factors: the roofmg material texture which slows down the flow; evaporation; and ineffiaencies in the collection process. WHAT TYPE OF ROOFING MATERIAL? If you ace planning a new mnshuc[ion project, metal roofmg is the preferred material because of its smooth surface and durability. Other material optlons such as clay file or slate are also appropriate for rairnvater intended to be used as potable water. These surfaces can be treated with a speaal painted coating to discourage bacterial growth on an other- wise porous surface. Because composite asphalt, asbestos, chemically treated wood shingles and some painted roofs mold ]each toxic materials into the rainwater as it touches the roof surface, they are recommended only for non-potable water uses. ® For systems intended as potable water sources, no lead is to be used as roof flashing or as gutter solder as the slightly acid quality ofrain can dissolve the lead and thereby contaminate water supply. Existing houses and buildings should be hilly examined for any lead content in the planning stages of any rainwater collection project. CATCHIVIF,N'I' AREA SIZF. The size of a roof catchment area is the building's footprint under the roof The catchment surface is limited to the area of roof which is guttered. To calculate the size of your catchment area, multi- ply the length times the width of the guttered area (See Chapter VI for more detail). CALCULATING CATCHMENT AREA h ' ~ ROOF -' ~ ~ -___kREA _r-' i ~ ~ ~ -' -' `"~ ---~._. ~ ~~ 0 1 ' 0 ®~ i •' s ® ® ' __ l b '-_- B. GUTTERS AND DOWNSPOUTS These are the components which catch the rain from the roof catchment surface and transport it to the cistern. Standard shapes and sizes are easily ob- tained and maintained, although custom fabricated profiles are also available to maximize the total amount of harvested rainfall. Gutters and down- spoutsmust beproperly sized, sloped, and installed in order to maximize the quantity of harvested rain. MATERL4LS AND SIZES. The most common material for off-the-shelf gutters is seamless aluminum, with standard extnrsions of 5 inch and 6 inch sections, in 50 foot lengths. A 3 inch downspout is used with a 5 inch gutter and a 4 inch downspout is used with a 6 inch gutter Galva- nized steel is another common material which can be bent to sections larger than 6 inches, in lengths of 10 feet and 20 feet. A seamless extruded aluminum 6 inch gutter with a 4 inch downspout can handle about 1,000 square feet of roof area and is recom- mended for most cistern installations. For roof areas that exceed 1,000 square feet, larger sections of gutters and downspouts are commonly fabricated 7 How Dces a Rainwater Harvestlng System Work? EXAMPLE OF A COMMERCIALLY AVAILABLE ROOF WASHER WITH FILTER SYSTEM ~W EXAMPLE OF A STANDPIPE TYPE ROOF WASHER Leal Sae Gulls Ra from galvanized steel or the roof area is divided into several guttered zones. Downspouts are designed to handle 1.25 inches of rainfall during a 10 minute period. Copper and stainless steel are also used for gutters and downspouts but at far greater expense than either aluminum or galvanized steel Downspouts are typi- cally the same material as the gutters but of a smaller cross section. The connection between the downspout to the astern is generally constructed of Schedule 40 PVC pipe. To keep ]eaves and other debris from entering the system, the gutters should have a continuous leaf screen, made of 1/4 inch wire mesh in a metal frame, installed along their entire length, and a screen or wire basket at the head of the downspout Gutter hangers are generally placed every 3 feet The outside face of the gutter should be lower than the inside face to encourage drainage away from the building wall. Where possible, the gutters should be placed about 1/4 inch below the slope line so that debris can dear without knocking down the gutter. ® As with theca[chment surface, it is important to ensure that these conduits are fife of lead and any other treatment which could contaminate the water. Check esperlallyifyou are retrofitting onto oldergutters and downspouts that may have lead solder or lead-based paint. ROOF WASHERS Roof washing, or the collection and disposal of the first flush of water from a roof, is of particular concern if the collected rainwater is to be used for human consumption, since the first flush picks up most of the dirt, debris, and contaminants, such as bird droppings that have collected on the roof and in the gutters during dry periods. The most simple of these systems consists of a stand pipe and a gutter downspout ]ocated ahead of the downspout from the gutter to the dstem. The pipe is usually 6 or 8 inch PVC which has a valve and clean out at the bottom. Most of these types of roofwashers extend from the gutter to the ground where they are supported. The gutter downspout and top of the pipe are fitted and sealed so water will not flow out of the top. Once the pipe has filled, the rest of the water flows to the downspout connected to the dstern. These systems should be designed so that at least 10 gallons of water are diverted for every 1000 square feet of collecton area. Rather than wasting the water, the first flush can be used for non- potable uses such as for lawn or garden irrigation. Several types of commerdal roof washers which also contain filter or strainer boxes are avai]able. ® Consider trimming any tree branches that overhang the roof. These branches are perches for birds and produce leaves and other debris. 8 Courtesy o(Wafer Fll[ratlan Company Texas Guide to Rainwater Harvesting C. STORAGE TANKS Other than the roof, which is an assumed cost in most building projects. the storage tank represents the larg- est investment in a rainwater harvesting system To maximize the effiaency of your system, your building plan should reflect decisions about optima] placement, capadty, and material selection for the astern. STTING In Texas, recently installed dytems are placed both above and below ground. While above ground instal- lations avoid the costs associated with excavation and certain maintenance issues, cisterns that are below ground benefit firm the cooler year-round ground temperatures. To maximize effiaency cisterns should be located as close to both the supply and demand points as possible. And, to facilitate the use of gravity or lower sttr_ss on a pump, the ostem should be placed on the highest level that is workable. While the catchment area (roof) should not be shaded by trees, the cistern can benefit from the shade since direct surilight can heat the stored rainwater in the tank and thereby encourage algae and bacterial growth, which can lower water quality. Texas does not have spedfic regulations concerning rainwater systems; however, to ensure a safe water supply, dstems should be sited at least 50 feet away from spumes of pollution such as animal stables, latrines, or, ff the tank is below grourxf, fiorn septic fields. Tank placement should also take into consideration the possible need to add water to the tank from an auxiliary spume, such as a water truck, in the event your water supply is depleted due to over-use or drought conditions. For this reason, the cistern should be located in a site accessible to a water truck, prefer- ably near a driveway or roadway, and positioned to avoid crossing over water or sewer lines, lawns or gardens. DESIGN FEATTJRE$ Regardless of the type of tank material you select, the astern should have a durable, watertight exterior and a clean, smooth interior, sealed with anon-toxic joint A TYPICAL STORAGE CISTERN flow sealant If the water is intended for potable use, the tank should be labeled as FDA-approved (Food and Drug Administratioh), as should any sealants or paints used inside the tank Alight-fitting mver is essential to prevent evaporation, mosquito breeding, and to keep insects, burls, lizards, frogs and rodents from entering the tank. If the tistem is your only water spume, an inflow pipe for an alternate water source is advisable. All tanks, and especially tanks intended for potable use, should not allow sunlight to penetrate or algae will grow in the cistern. A settling compartment. which encrourages any roof nrnoff sediment that may enter the tank to settle rather than be suspended in the tank, is an option that can be designed into the bottom of the dstem. Designing a system with two tanks provides some fle~dbility that may be of value. Irr most cases, an additional tank represents added cost, regardless of whether it represents increased capacity. This is be- causetwo smallertanks of, for example,1,500 gallons each are generally mote expcrlsive than a single 3,000 gallon tank The primary benefit of a multi-tank system is that the system tan remain operational if one tank has to be shut down due to maintenance or leaking. Regardless of tank type chosen. regular inspection and proper maintenance are imperative to ensure reliability and safe, effident operation. Remember that water is heavy. A 500 gallon tank of water will weigh more than two tons, so a proper foundation and support are essential 9 How Dces a Rainwater Harvesting System Work? MATERIALg Tanks are available in a range of materials and sizes, new and used, large and small, to accommo- date your system design and budget. For small installations, readily available new and used tanks, including whiskey barrels, 55-gallon drums, and horse troughs can be fashioned into supplemental do-it-yourself systems. If used tanks are selected, be sure that they did not contain any toxic sub- stances which could affect water quality for many, many years. For large installations, many options exist for manufactured and site-built systems, as described below. Concrete and Masonry Concrete. Reinforced concrete tanks can be built above or below ground by a commercial contrac- tor orowner-builder. Because of their weight, they are usually poured in place to specifications and are not portable. However, concrete tanks can also be fashioned from prefabricated components, such as septic tanks and storm drain culverts, and from concrete blocks. Concrete is durable and long-lasting, but is subject to cracking; below- ground tanks should be checked periodically for leaks, especially in clay soils where expansion and contraction may place extra stress on the tank. An advantage of concrete cistern chambers is their ability to decrease the corrosiveness of rainwater by allowing the dissolution of calcium carbonate from the walls and floors. Ferrocement. Ferrocement is a teen used to de- scribe a relatrvely low-cost steel-mortar composite material. Its use over the past 100 years has been most prevalent in developing countries in a range of lowcost applications, such as water tanks. It has also gained popularity among do-it-yourselfers in Texas and throughout the U.S. Although it is a form of reinforced concrete, its distinctive charac- teristlcs relative to performance, strength, and flex- ible design potentials generally warrant classifica- tion of fermcement as a separate material. Unlike 10 reinforced concrete, ferrocement's reinforcement is comprised of multiple layers of steel mesh (often chicken wire), shaped around a light framework of rebar, that are impregnated with cement mortar. Because its walls can be as thin as 1", it uses less materials than conventional poured-in-place con- crete tanks, and thus can. be less expensive. Ferrocement lends itself to low-cost construction projects, since it can take advantage of self-help labor and prevalent, low-cost raw materials such as rebar, chicken wire, cement and sand. Fenncement tanks are likely to require greater ongoing mainte- nance than tanks constructed of other materials. Small cracks and leaks can be easily repaired with a mixture of cement and water, and also applied where wet spots appear on the tank's exterior. Some sournes recommend that it is advantageous to paint above-ground tanks white to reflect the sun's rays, reduce evaporation, and keep the water cool. Though ferrocement is most commonly asite-built method, commertaally available ferrocement tanks are available in some parts of Texas. Check to be sure that the fetrocement mix does not contain any toxic compounds which may make the water unfit for use. Stone. Across the Texas Hill Country and other parts of the state with abundant rock, site-built stone cisterns were historically a logical approach to tank fabrication since the materials were locally avail- able. The mass of the stone walls helps to keep interior water temperature cool, and the tanks can be designed to blend in with adjacent buildings. Some recent installations, such as the National Wildflower Research Center in Austin, have contin- ued the tradition of stone cistems. As with cement tanks. these installations are permanent. Constnrc- tlon procedures should be careful to exclude any compounds which may be toxic, such as some types of mortars and sealants, especially if the system is planned for potable water. Texas Guide to Rainwater Hanrestlng Plastic Fiberglass. Fiberglass tanks are lightweight, reason- ably priced, and long lasting, making them one of the most popular tanks in contemporary installa- tions. As with the polyethylene and galvanized tanks, fiberglass tanks are commercially available throughout the state and easy to transport They are available in a wide range of sizes and can be specified for potable water. Fiberglass tanks should be coated or constructed to prevent penetration of sunlight into the tank. Plastic Liner. Plastic liners are sometimes used to line concrete tanks or tanks that have developed leaks. These liners can also be used to line low- cost, temporary collection tanks constructed of materials such as plywood. Plastic liners that are specified for potable use are commercially avail- able. It is important to remember when using liners that they must be fully supported since they have no structural strength of their own. If a 1 1 ~., DEPTH (feet) 6 FOOT DIAMETER ( 12 FOOT gRMETER 78 F007 DIAMETER gallons) (gallons) (gallons) 6 1,266 5,076 11,412 8 1,688 6,768 15,216 10 2,110 8,460 19,020 12 2,532 10,152 22,824 14 2,954 11,644 26,628 16 3,376 13,536 30,432 18 3.798 15,228 34,236 20 4,220 16,920 38,040 wooden form is used, remember that it should be protected from the elements since it will tend to rot quickly. Polyethylene. These tanks are commercially available in a variety of sizes, shapes, and colors, and can be constructed for above or below ground installations. Polyethylene tanks are gaining popularity due to -MATERIAL FEATURE CAUTION PLASTICS Gazbage Carts (20-50 ga0on) commercially available, inexpensive use only new taro Fiberglass ' commercially available, degradable, requires interior coating alterable and moveable Polyethylene/Polypropylene commerdally availab]e, degradable, requires exterior coating alterable and moveable METALS Steel Dnrms (55 gallon) commercially available, verify prior use for toxics wrmdes and alterable and moveable , rusLS, small capacity Galvanized Steel Tanks commercially available, possible corrosion and rust alterable and moveable CONCRETE AND MASONRY FerTncement dumble, immoveable potential to crack and fail Stone, Concrete Block durab]e, immoveable difficult to maintain Monolithic/Poured in Place dumble, immoveable potential [o crack WOOD Redwood, Douglas Fir, Cypress attractive, durable expensive 11 How Dces a Rainwater Harvestlng Sys[em Work? their relatively low cost and long life expectancy- theyare considered slightly more durable than fiber- glass with comparable life expectancy. Their light weight makes them easy to transport and relocate, if needed, while their smooth interior surface makes them easy to clean. Repairs are relatively easy to carry-out-use heat to soften the plastic and reshape as necessary. To ensure their long-life, polyethylene tanks should be chosen which have ultra-violet (lJ~ inhibitors for outdoor use, or can be placed in an enclosure or painted with a protective surface to provide protection from the sun. Black tanks have the greatest W resistance, with a life expectancy of 25 year;, though will tend to absorb heat and thus can affect water quality. Painting or shading the tank will minimize the effects of W light and is recommended. Again, light penetration will pro- mote algae growth. Ifyou intend to use the tank for potable water, be sure that it is FDA approved. Metal Galvanized Steel. Steel tanks were a predominate choice by those early Texans who did not have stone nearby, and continue to be a popular choice in Texas today. Galvanized steel tanks are commercially available and reasonably priced. They are noted for their strength, yet are relatively lightweight and easy to move. Corrosion ran be a problem if exposed to aadic conditions; some suppliers provide an inside liner to guard against this problem. In addition, high and ]ow pH water conditions can result in the release of zinc. As with other tank materials, be sure that any galvanized metal tank used as a potable water soun;e is FDA approved. If salvaging an old metal tank, be aware that these were generally soldered with lead and should not be used as a potable water soume. Wood Redwood and Cypress. Redwood is considered one of the most durable woods for outdoor use, though is uncommon in Texas since it is not a native wood species. Cypress is a natve Texas wood with many of the same pmpetties as redwood. Although cy- press was used to construct cisterns in Texas in the early 1900's, cypress tanks are not commertially available today. Redwood has a reputation as durable water storage tank material, and is attrac- tive because it has no resins that could affect the odor or taste of water, has high levels of tannin, a natural preservative which makes the tank resistant to insects and decay, and has a cellular construction which allows for complete saturation from capillary and direct pressure and enhances its capacity to retain moisture. In addition, redwood is an efficient insulator, which keeps water cooler in summer and protects it from freezing temperatures in winter, does not rust or corrode and requires no painting or preserving. Redwood tanks have an average life expectancy of 50 years, with some known to last as long as 75 years. D. CONVEYING Remember, water only flows downhill unless you pump it. The old adage that gravity flow works only if the tank is higher than the kitchen sink accurately portrays the physics at work. The water pressure for a gravity system depends on the differ- ence in elevation between the storage tank and the faucet. Water gains one pound per square inch of pressure for every 2.31 feet of rise or lift. Many plumbing fixtures and appliances require 20 psi for proper operation, while standard municipal water supply pressures are typically in the 40 psi to 60 psi range. To achieve comparable pressure, a cistern would have to be 92.4 feet (2.31 feet X 40 psi = 92.4 feet) above the home's highest plumbing fixture. That explains why pumps are frequently used, much in the way they are used to extract well water. Pumps prefer to push water, not pull it. To approximate the water pressure one would get from a municipal system, pressure tanks are ofren installed with the pump. Pressure tarilcs have a pres- sureswitch with adjustable settings between 5 and 65 psi. For example, to keep your in-house pressure at about 35 psi, set the switch to tum off the pump when 12 Texas Guide ro Rainwater Harvesting the presstue reaches 40 psi and ttun it on again when the pressure drops down to 30 psi. E. WATER TREATMENT Before making a decision about what type of water treatment method to use, have your water tested 6y an approved laboratory and determine whether your water will be used for potable or non potable uses. The types of treatment discussed are filtration, disinfection, and buffering for pH control. Dirt, rust, scale, silt and other suspended particles, bird and rodent feces, airborne bacteria and cysts will inadvertently find their way into the cistern or storage tank even when design feattues such as roof washers, screens and tight-fitting lids are properly installed. Water can be unsatisfactory without being unsafe; therefore, filtration and some form of disinfection is the minimum recommended treat- ment if the water is to be used for htunan consump- tion (drinking, brushing teeth, or cooking). The types of treatment units most commonly used by rainwater systems are filters that remove sediment, in consort with either an ultraviolet light or chemical disinfection. FII.TERS Filtration can be as simple as the use of cartridge filters or those used for swimming pools and hot tubs. In all cases, proper filter operation and mainte- nance in accordance with the instruction manual for that specific filter must be followed to ensure safety. Once large debris is removed by screens and roofwashers, other filters are available which help improve rainwaterquality. Keep in mind that most filters on the market are designed to treat municipal TREATMENT TECHNIQUES rnErxoo tacnnax aESUtr SCREENING Strainers and Leaf Screens Gutters and Leaders Prevent leaves and other debds firm entering tank SETTLING Sedimentation Within Tank Settles oarticulate matter FII.TERIlVG In-Line/Mold Cartridge After Pump Sieves sediment Activated Charcoal At Tap Removes chlorine' Reverse Osmosis At Tap Removes contaminants Mixed Media Separate Tank Traps particulate matter Slow Sand Separate Tank Traps particulate matter DISINFECTING Boiling/Distilling Before use Kills microorgarrisms Chemical Treatments (Chlorine or Iodine) Within Tank or At Pump Kills micrmrganisms (liquid, tablet or granule) Ultraviolet Light Ultraviolet light systems Kilk microorganisms should be located after the activated carbon filter before trap Ownation Before Tap Kflls micmotganisrm ' 4nildadyheuaedaRadYairem iod~e hasbmiused asa divdarmt Uiaavide light and mne systerts should 6e loarai a@er rheadrvakdadxri ftller6u before the rap 13 water or well water. Therefore, filter selection re- quires careful consideration. Screening, sedimentaton, and prefiitering occur between ptchment and storage or within the tank. A camidge sediment filter, which traps and removes particles of five microns or larger is the most com- mon filter used for rainwater harvesting. Sediment filters used in series, referred to as multi-cartridge or in-line filters, sieve the particles from increasing to decreasing size. These sediment filters are often used as a pre- filter for other treatment techniques such as ultra- violet light or reverse osmosis filters which can become clogged from large particles. Unless you ate adding something to your rain- water, there is no need to filter out something that is not present. When a disinfectant such as chlorine is added to rainwater, an activated carbon filter at the tap may be used to remove the chlorine prior to use. Remember that acfivated cazbon filters aze subject to becoming sites of bacterial growth Chemical disinfectants such as chlorine or iodine must 6e added to the water prior to the activated carbon filter. ff ultraviolet light or ozone is used for disinfection, the system should be placed after the activated carbon filter. Many water treatment standards require some type of disinfection after filtration with activated carbon. Ultraviolet light disinfection is often the method of choice. All filters must be replaced per recommended schedule rather than when they cease to work; failure to do so may result in the filter contributing to the water's contaminatron. DISINFECTION Ultraviolet Light (UV) water disinfection, a physical process, kills most microbiological organisms that pass through them. Since particulates offer a hiding place for bacteria and microorganisms, prefiltering is necessary for W systems. To determine whether the minimum dosage is distributed throughout the disinfection chamber, UV water treatment units should be equipped with a light sensor. Either an How Dces a Rainwater Harvrstlng System Wnrk? alarm or shut-off switch is activated when the water does not receive the adequate ]evel of W radiation. The W unit must be correctly calibrated and tested after installation to insure that the water is being disinfected. Featured in the case studies are several systems which utilize ultraviolet light Ozone is the disinfectant of choice in many European countries, but it has not been used in American water treatment facilities until recently. Ozone is a form of oxygen (0~ produced by passing air through a strong electric field. Ozone readily kills microorganisms and oxidizes organic matter in the water into cazbon dioxide and water. Any remaining ozone reverts back to dissolved oxygen (0~ in the water. Recent developments have produced compact ozone units for home use. Since ozone is produced by equipment at the point of use with electricity as the only input, many rainwater catchment systems owners use it to avoid having to handle chlorine or other chemicals. Ozone can also be used to keep the water in cisterns "fresh". When used as the fmal disinfectant, it should be added prior to the tap, but after an activated carbon filter, if such a filter is used. Chlorine or iodine for disinfecting. Private systems do not disinfect to the extent of public water systems where the threat of a pathogenic organism such as e. roll can affect many households. If the harvested rainwater is used to wash clothes, water plants, or other tasks that do not involve direct human consumption or contact, treatment beyond screening and sedimentation removal is optional. However, if the water is plumbed into the house for genera] indoor use such as for drinking, bathing, and cooking, disinfection is needed. While filtering is quite common in private water systems, disinfection is less common for these reasons: the Safe Drinking Water Act is neither enforced nor applicable to private systems; chlorine is disliked due to taste, fear associated with trihalomethanes (THMs), and other concerns. Chlo- rine is the most common disinfectant because of its dependability, water solubility, and availability. 14 Texas Guide to Rainwater Harvesting Granular or tablet form is available (calcium hypochlorite), but the recommended application for rainwater disinfecting is in a liquid solution (sodium hypodilorite). Household bleach contains a 5.0% solution of sodium hypochlorite, and is proven to be reliable, inexpensive and easily obtained. A dose is one liquid ounce of bleach for each 100 gallons (one and a quarter cups of bleach per 1,000 gallons) of rain- water collected will most likely be sufficient to disinfect the collected rainwater. When disinfecting. never overdose with bleach. Mixing occurs natu- rally over a day or so, but a clean paddle may be used to accelerate the process. When chlorine bleach is added directly to the storage tank or cistern as described above, the chlorine will have a longer time to kill bacteria thus achieving a better rate of disinfection. Chlorine feed pumps which release small amounts of solution while the water is being pumped can also be used. Chlorine metering pumps inject chlorine into the water only at the time of use. Chlorine concentrations are easily measured with a swimming pool test kit A level of between 0.2 mg/L (milligrams per liter) and 1.5 mg/L is recom- mended. If the level is below 0.2 mg/L, add one liquid ounce of chlorine bleach per 100 gallons of the volume of water in storage (one and a quarter cups per 1,000 gallons) if you are using bleach or adjust the chemical feed pump in accordance with the pump's instructions. ® Swimming pool test kit chemicals are toxic and should never be allowed to mix with cistern water. Testing should occur outside [he tank Chlorine is more effective at higher water tem- peraturesand lower pH levels than iodine. Iodine is another water disinfectant that is less soluble than chlorine although it is effective over a pH range of 5 to 9 and displays greater antibacterial activity in water temperatures of 75 to 98.6 degrees Fahrenheit. ® Prolonged presence of chlorine where organic matter may bepresent may cause the formation of chlo- rinated organic compounds. If chlorine is used as a dis- infectant, 6e sure to screen all,organic material from the tank. BUFFERING Baking soda for buffering. The composition and pH of rainwater differs from chemically treated municipal water and mineral rich well water. Controlling the pH of rainwater by buffering can be easily accom- plished by adding one level tablespoon of baking soda to the storage tank for each 100 gallons of water collected. (About four ounces by weight of baking soda for every 1,000 gallons of water collected.) An easy method is to mix this amount of baking soda in ajar of water and pour it into the tank. Mixing will occur naturally over a day or two or a dean paddle may be used to hasten the process, but avoid disturb- ing materials that have settled at the bottom of the cistern. OTHER TREATMENT There are a ntrrnber of other treatment devices available on the market When selecting additional treatment devices, always ask yourself what is it that you are trying to munove, does it need to be removed, and does this water source contain that contaminant. Commerdal and public test laborato- ries can help in this regard. Some of the types of treatment available include reverse osmosis (RO) and nano-filtration, and sev- eral other "membrane" processes and distillation equipment that are designed primarily to remove dissolved materials such as salts or metals, but rainwater contains extremely low dissolved salts or hardness levels. For the most part, systems such as RO would be redundant and expensive to use. Besides, most home RO units waste three to five gallons of water for every gallon of water produced. As a word to the wise, consult your local health department before purchasing such devices. Some devices are actually dangerous if used incorrectly. 15 ' ~ Texas Cuide to Rainwater Harvesting V. HOW MUCH WATER DO YOU USE? ssessing your indoor and outdoor water needs will help determine the best use for the rainwater. If you are already connected to a municipal water system, then a rainwater harvesting unit designed to fulfill outdoor requirements such as lawn and garden irrigation may be most cost-effective. If you have already invested in a well-water system, rainwater could augment or enhance the quality of mineral- ized well water for purposes such as washing, or provide back-up water when underground water sources are low Some people are installing afull- service rainwater system designed to supply both their indoor and outdoor water needs. ff you are considering this option, it is imperative that you employ best conservation practices to ensure ayear- round water supply. 'Three variables determine your ability to fulfill your household water dfL mand: your local precipitation, available catchment area, and your fmancia] budget. If you are accustomed to simply turning on a tap to get your water and then paying a bill at the end of the month, the switch to a rainwater system will require some adjustment. While the assoriated tasks are not difficult, they are important to keep your water safe and your family in good health. These responsibilities include regular inspections of all the previously discussed components, including FIXTURE USE FLOW RATE i OF USERS 70T~L Toilet # flushes per person per day 1.6 gallons per flush (new toile[)' Shower # minutes per person per day 2.75 gallon per minute` (5 minutes suggested max.) (testriaed flow head) ~~ # baths per person per day 50 gallons per bath (a~Be) Faucets bathroom and kitchen sinks 10 gallons per day not applicable (excluding cleaning) M ~~ # loads per daY 50 gallons per load not app]cable (average) Dishwasher # loads per day 9.5 gallons per load not applicable Total # gallons/day multiply (x) 365 # gallons/year 'All of the Flow rates shown are for new fixtures. Older toilets use from 3.5 to 7 gallons per Flush, and older shower heads have flow ates as high as 10 gallons per minute. 16 How Much Water Do You Use? pruning branches that overhang roof, keeping leaf screens clean, checking tank and pump, replacing filters, and testing the water. A maintenance schedule and checklist based upon your partic- ulaz system are recommended to ensure proper performance. HOUSEHOLD WATER BUDGET An easy way to calculate your daily water consump- tion is to review previous water bills, if you pres- ently receive municipal water. Another method is to account for every water-using activity including shower, bath, toilet flush, dishwashing nm, washing machine load. A conserving household that has low- flow plumbing fixtures such as 1.6 gallon-per-flush toilets and 2.75 gallon-per-minute shower heads, now required by the Texas Plumbing Standazds, might use 55 gallons or less of water per day per person and very conservative minded households might be able to reduce water use to as low as 35 gallons per person per day. However, for the pur- poses of designing a rainwater system, an estimate of 75 gallons per person per day for indoor use is advised to ensure adequate yeaz-round indoor wa- ter supply -unless you are sure that all of your NOMEINDOOR WATER USE Homes with older Fixtures use about 75 gallons per person per day (GPCD) Bathing Dishes 3% 12% Toilet Laundry _ 2a% 22% Leaks 5% BASE AND SEASONAL WATER USE IN TEXAS 65% 35% fixtures aze the newer, more efficient ones and you plan to follow strict Lronservation practices. Com- plete the Household Water Consumpfion Chart on page 16 to see how your household's water con- sumption compares with the recommended design allowance. See page 18 for outdoor use estimates. While inside water use' remains relatively level throughout the year, total water demand increases during the hot, dry summers due to increased lawn and garden watering, and decreases during the cool, wet winters when the garden is fallow and the lawn needs little attention. To determine your daily water budget, multiply the number of persons in the household times the average water consumption. Estimates of indoor household water use range from less than 55 gallons per person a day in a 16% 17 Homes withwater-saving fixtures use about 55 gallons per person per day (GPCD) Bathing 29% Laundry 37% :"/ Dishes 4% Toilet 12% Leaks 8% WirnH Summer Wisner TexasCuidetoRainwa[erHarvesting ~.~~ yr ~~ ~ ~ ~ t'• ~IdtvL +',y.,,~ •WN ~ ~ ` it~ii W~Iv .~., ...s HOME WATER USE, INDOOR AND OUTDOOR conservation minded household to well over 75 gallons per person a day in non-conserving house- holds. LANDSCAPE WATER BUDGET In order to calculate a water budget fora conven- donal lawn, you must determine the grass type, the square footage of your lawn, and your annual rainfall. If the average annual rainfall for your area is ~ ~. , GR0.5$ TYPE AND THEIR WATER OENUWD St Augustine 50 Inches per year Buffalo Grass 25 inches per year higher than the requited water demands listed be- low,your annual rainfall is sufficient If your annual rainfall is lower than the required inches based on grass type, you will need to complete the following chart to determine your lawn watering require- ments in order to properly size your cistern. WATER CONSERVATION TECHNIQUES While rainwater collection qn function weU as a stand alone system, its efficiency can 6e enhanced 6y working in concert with other water conservatlon practices. Reducing your water demand results in lowering the up front cost of your rainwater harvesting system. SAVING WATER INSIDE YOUR HOUSE If your water budget or water bill indicates usage beyond your collection capadty, common sense wa- terconservation practices might help you to recover those extra gallons. The repair of dripping faucets and leaking toilets, frequently the soutce of much lost water, is a good start. Installing low-flow showerheads, faucet aerators and toilet dams are other steps that pay for themselves in less than a yeaz through water savings. Water conserving dish washers and clothes washing machines that operate with half as much water as conventional appliances ~ ~. Bermuda 40 inches per year S[ Augus[ine/ 95 inches per year Bermuda Mix Zoysia 45 inches per year 1. Multiply the water demand (inches per year) times your lawn size (square feet) and divide by 12. This will give you the cubic feet of of water demand per year. ~, g. 2. Multiply the number cubic feet of water demand per year (line i) times a conversion factor of 7.48. This gives you the number of required gallons of water per year. gy], 3. Multiply the inches of natural rainfall for your area (see page 20) times your lawn size (square feet) and divide by 12. This gives you the cubic feet of water supplied by natural rainfall. nt. fr. 4. Multiply the cubic feet of natural rainfall times a conversion factor of 7.48. This gives you the gallons of natural rainfall per yeaz. g~ 5. Subtract the gallons of natural rainfall (line 4) from the required water demand for your grass type (line 2). This gives you the gallons required. gyl 18 are also available. The Texas Water Development Board and your local water utility have more infor- mation on ways to conserve water in your bath- room, kitchen, and laundry. SAVING WATER OUTSIDE YOUR HOUSE Landscape irrigation accounts for about one-quarter of all municipal water use in Texas. The most inten- sive time to irrigate is the summer growing season, which is when temperatures are highest and rainfall is lowest. Rainwater becomes particularly precious during these hot, dry months. Indeed, rainwater 19 How Much Water Do You Use? used for summer irrigation must be captured earlier in the year Therefore, a landscape that requires minimum watering, especially in the summer, is most appropriate for rainwater harvested irrigation. The use of regionally-adapted drought tolerant and low water use plants is also a major help. Drip. Irrigation. Trickle or drip irrigation is the frequent, low pressure application of small amounts of water to the soil area directly surround- ing the plant roots. A constant level of soil moisture is maintained, even though up to 60% less water ., Texas Cuide to Rainwater Harvesting than conventional watering is used by this method. The efficiency and uniformity of a low water flow rate reduces evaporation, nrn-off, and deep perco- lation. Acommon soaker hose, usually installed below ground, is one of the simplest ways to drip irrigate shrub beds, gardens and young trees. ®To obtain more information about Water Wise landscaping, tlnp irrigation, and indoor water conserva- tion techniques, contact the Texas Water Development Board at Conservation, P.O. Box 13231, Austin, TX 78711-3231 or the Texas Department of Agriculture, city utility, river authority, or your county agriculture extension agent. Greywater Reuse. In urban areas, public policy and health codes generally mandate the centralized col- lection and treatment of household wastewater. Policy discussions relating to greywater reuse are underway, reflecting concern to mardrnize water use options brought on by droughts, water shortages, and development impacts on existing wastewater treatment facilities. Greywater reuse, which relies on separating the greywater from the blackwater, has many environmental and economic benefits on both the building and regional scales. Because greywater is relatlvely benign, it can be directed to a number of secondary uses such as toilet flushing and irrigation, 7 WATER WISE PRINCIPLES thus displacing the need to use higher quality water. Greywater is household wastewater generated by clothes washing machines, showers, bathtubs, and bathroom sinks. Wastewater from kitchen sinks is excluded from this gtegory since it contains oil, Fat, and grease which are difficult to filter, clog distribu- tion pipes, have unpleasant odors, and ate likely to attract pests. Blackwater is the water flushed down toilets and urinals and also includes the discharge from kitchen sinks due to the reasons stated above. If a sanitary sewer connection is not available, blackwater must be treated on site by a septic tank, drain field, or a permitted on-site wastewater treatment system. Greywater can contain harmful bacteria and therefore also requires filtration and disinfection prior to reuse. Once the greywater is properly treated, it can be reused for irrigation and used to supplement higher quality rainwater. Always con- sultyour local health department. ® If you plan to incorporate a greywater system, check with your local health department o@'iaa/s since certain restrictions regarding installation and reuse apply. For example, greywater systems with overflows to public sewer systems cannot tie connected to rainwater systems. 1. Planning & Design that considers topography, existing vegetadon, and grouping plants and grasses by their watering needs. 2. Soil Improvement to prevent erosion and adding organic material, such as / compost, to promote water penetration and retention. f~l 3. Appmpriate Plant Selection such as native and adapted plants that use less water and are more resistant to diseases and pests. 4. Practical irrigated turf and landscaped areas in appropriate locations to be separate]y irrigated. 5. Efficient Watering by avoiding watering until absolutely necessary and never watering in the heat of the day or on windy days to avoid evaporation. 6. Use of Mulches to cover and shade soil, minimize evaporation, reduce weed growth and soil erosion. 7, Lower Maintenance by the decreased use of pesticides and fertilizers. 20 1 How Much Water Do You Use? Other Water Reuse Options Under new rules from the Texas Natural Re- sourees Conservation Commission (TNRCC), wa- ter fmm on-site sewage facilities, such as septic systems, can now be reused for landscape irriga- tion after proper secondary treatment and disin- fection. Contact your local health department or the TNRCC at P.O. Box 13087, Austin, Texas 78711-3087. The applicable rule is 30 TAC285. You can also download the Wile from the TNRCC's web site at http://wwwhtrcc.state.tx.us. 21 ' - Texas GWde t° Rainwater Harvesting VI. HOW MUCH RAINFALL CAN YOU COLLECT? ow that you have a better understanding of the principles of rainwater catchment, the next questions are, how much rain can you expect to collect in your location and how reliable is this rainfall. The simple answer to the first question is that one inch of precipitation (1/12 foot) on one square foot of collection area equals 0.6233 gallons. Many simply round this off to 600 gallons collected per inch of rain on 1,000 squaze feet. From this basic Wile of thumb (600 gallons per inch on 1,000 square feet) the analysis shifts to (1) how efficiently can this rainfall be collected, and (2) how reliable is the rainfall on your specific area. Once these questions are answered, you will need to balance the amount of rainfall than can be collected with the amount of water that will be used. You may be surprised to learn that even with the strictest water conservation measures, rainfall collection can only provide a fraction of the amount of water you use. The answer to these questions also depends in part on what the harvested rain will be used for If it is to provide supplemental water for the yazd, the answer will be different than if the system will be the sole source of water for a household. One should also keep in mind that the efficiency of the collection system can change depending on design while the question regarding precipitation reliability depends on where you are located. Colleecion E~rrenry. How efficiently the rainfall can be collected depends on several considerations. Many first assume that "I can collect all of it," but this is never the case. First, there is always a small loss to rainfall needed to wet the roof area and water collected by the roof washer. This is usually a small percentage of the rainfall and will range from about 3/100's to 1/10th of an inch per rainfall event, depending on the roof material and the volume the roof washer diverts. Built-up flat roofs can retain as much as half an inch of water depending on their condition and design. Overshot of gutters and spillage during very intensive rainfall events will occur. Spills and rate of rainfall can also make a difference. If filter type roof washers are used, they will "spill" the excess flow once the filter flow through capacity is exceeded. Finally, you can collect only as much rainfall as your storage system will hold. Depending on your design, most cisterns will become full during especially rainy periods and any additional rainfall collected will spill. Collection efficiencies of 75% to 90°~ are often used by installers depending on the specific design if the system is to provide water for in-home use. For small systems designed for supplemental plant watering, collection factors of below 50% are common because it is not economic to install the large storage that would be required to increase this factor. Rainfall Reliability. The reliability of precipi- tationrequires acloser look. The first and sim- plestparameter to consider is average precipi- tation. The map on page 19 shows average precipitation for Texas. The first step one should take is to use the average rainfall for your area to determine how much water 22 How Much Rainfall Can You Collect? would be generated from your roof area. The calculation is the roof catchment area times the average rainfall times 600 gallons divided by 1,000. Area (ft~ X Average Rainfall (inches) X 600 1,000 If you are only interested in supplemen- talwater for plant watering, this maybe suf- ficient knowledge, but if rainwater is to be your sole source of water, you need to know what precipitation rate you can rely on in more detail. Once your system is in, you will need to know the amount of rainfall you can ex- pect from one month to the next. The figure on page 24 shows annual pre- cipitation for seven cities from across Texas. The annual rainfall is arranged in rank order from the lowest to the highest for each city. This graph also shows the percent of time that rainfall of that magnitude will not be ex- ceeded. For example, the graph shows that in Wichita Falls, rainfall will be greater than 30 inches per year about 35% of the time or lower than 30 inches per year 65% of the time. The graph also indicates that annual rainfall in Wichita Falls will fall between 17 inches but below 37 inches 90°~ of the time. As a rule-of-thumb in Texas, if one di- vides average annual rainfall by two, the re- sulting answer will be near the 5% percentile rainfall. For example, Austin receives an av- erage of 32 inches a year and only 5% of the time is rainfall less than 17 inches a year. This can help give a quick method of determining if enough rainfall will occur to provide water during very low periods based on annual pre- cipitation. An expample of how annual data can be used is shown below The monthly distribution of rainfall is also important information for sizing a sys- tem. Using annual data does not tell you how much water one can expect from one month to the next or just as important, once in op- eration, how much rainfall can one expect in any one given month. These statistics are pre- sented in "Rainfall Data for Selected Commu- nities Across Texas" on page 27. The use of these data is twofold. First, the 10%, 25% and 50% (median) monthly data present the percent of times that rainfall is less 1. Calculate Roof Catchment Area (see page 7) 2. Multiply the collection area in square feet by 0.6 gallons per square foot per inch of rain times the collection factor times the average annual rainfall and half of the average an- nual rainfall. For example, if you have 2,500 square feet of collection area and live in Austin, where the average annual rainfall is 32 inches a year and the collection efficiency factor is 80%, [he aver- ageamount ofrain you can collect is: 2,500 X 0.6 X 0.8 X 32 = 38,400 gallons per year 3. Dividing this by 365 days a year, the supply would be 105 gallons per day. 4. Using the rule-of--thumb that half of the average rainfall will provide a close estimate of the low expected rainfall for the area, in an extremely severe drought year, approxi- mately 19,700 gallons could be collected. This would result in a supply of only 53 gallons a day. 23 " Texas Guide ro R~nwata Harvesting y ~ .~ ~ V ~ ~ ~ X ~ ~ ._ F- _ ~ .O ,~,,, ._ C1 .~ ~ ci > ~ ~ ~ L ~ ~ Q N L ~ ¢ o ~ a ' o ~ ~ _ ~ ¢ m LL ~ ~ ~ l ~ .~ ~ =~ Y ~ .~ ~ ~ n. w 0 0 tAOtnOtt)OOOOO~OLnOtC>OLC~O O~titi000~~t'e!'MMNNe-e- uie~ ~o say~u~ 0 0 ~ ~ o~ ~ •- i- t°` O c°o ~ ~ as ~a O a' M •~ Y O C N ~ O O 24 How Much Rainfall Can You Collect? than that value. Examination of the data also value annual total is 12 inches which occurs shows that the 50% values are lower than the over 95% of the time. average values. This is because the arithmetic This information can also be used to de- average is skewed by a few abnormally high velop monthly balances'of demand and stor- rainfail events such as those occurring dur- ing hurricane. While the median represents the rainfall that, when all historic rainfall val- ues for that month are ranked from lowest to highest, is in the middle. The way to use these data on a monthly basis is that for any given month, you can ex- pect to get at least the median rainfall half of the time, the 25% rainfall 75°~ of the time, and the 10% rainfall 90% of the time. The sum of the twelve monthly median values is lower than the annual average as explained above. In Texas, the sum of the medial values pro- vides arainfall that can be relied on for 85% of the time or more. For example, the total for age as shown on the following page using Austin data. In this example, the median (50%) and 25% monthly rainfall were used. The pur- pose is to determine how much storage ca- pacity is needed and the level of demand that can be sustained. Different storage volumes, roof sizes (if this is an option), and monthly demands are tried. In the example case, the roof size is 3,000 square feet, the collection efficiency is 80%, and the storage volume is 10,000 gallons. It is assumed that the year begins with 3,000 th storage; monthly demands of 2,000 gallons, 3,000 gallons, and 4,000 gallons are used. The calculation is done by following the steps be- Austin is 25 inches which occurs 80% of the low. time in any given year and the 25% monthly 1. Determine January rainfall for both the 50% and 25% levels. For example, at the 50% rain- falllevel of 1.23 inches for January it is: 3,000 X 0.8 X 1.23 X 0.623 = 1,839 gallons collected 2. Add the volume already in storage (3,000 gallons) to the gallons collected and subtract the monthly demand. For the 2,000 gallons a month demand example and 50% rainfall level, this is: 1,839 + 3,000 - 2,000 = 2,839 gallons in storage at the end of the month This is repeated, but note that if the storage is zero or less at the end of the month, use zero for the next month; if the amount in storage at the end of the month is greater than the capacity of the cistern (10,000 gallons in this example) use the storage capacity for the end of the month storage. The end result is that for the 10,000 gallon storage capacity an anverge use of 3,000 gallons/month, but not 4,000 gallons/month, could be supported. Many professionals use 50 to 100 years of actual monthly rainfall data in a program which performs the same series of calculations as described above to determine the opti- mum system size. 25 1 ~ 1 ~ ~ 1 1 w 1 1 ' Monthly Rainfall End of Mo. ~ Rainfall End of Mo Use 50% rain Collected Storage 25% rain Collected . Storage (gal/mo ) (inches) (gallons) (gallons) (inches) (gallons) (gallons) 3,000 3,000 1 2,000 1.23 1,839 2,839 0.60 897 1,897 2 2,000 2.28 3,409 4,248 1.13 1,690 1,587 3 2,000 1.66 2,462 4,730 0.61 1,211 7g8 4 2,000 2.18 3,260 5,990 .1.38 2,063 861 5 2,000 3.89 S,B16 9,806 1.60 2,392 1,254 6 2,000 2.63 3,932 10,000 1.51 2,258 1,511 7 2,000 1.01 1,645 9,645 0.44 658 169 8 2,000 1.19 1,779 9,424 0.60 897 0 9 2,000 3.15 4,710 10,000 1.50 2,243 243 10 2,000 2.78 4,157 10,000 0.87 1,301 0 11 2,000 1.71 2,557 10,000 0.74 1,106 0 12 2,000 1.24 1,854 9,854 0.74 1,106 0 24,000 25.04 37,440 11.92 17,823 1 3,000 1.23 1,839 1,839 0.60 gg7 B97 2 3,000 2.28 3,409 2,248 1.13 1,690 0 3 3,000 1.66 2,482 1,730 0.81 1,211 0 4 3,000 2.18 3,260 1,990 1.38 2,063 0 5 3,000 3.89 5,816 4,806 1.60 2,392 0 6 3,000 2.63 3,932 5,738 1.51 2,258 0 7 3,000 1.01 1,645 4,383 0.44 658 p 8 3,000 1.19 1,779 3,162 0.60 897 0 9 3,000 3.15 4,710 4,872 1.50 2,243 0 10 3,000 2.78 4,157 6,029 0.87 1,301 0 11 3,000 1.71 2,557 5,586 0.74 1,106 p 12 3,000 1.24. 1,854 4,440 0.74 1,106 p 6,000 _ 25.04 37 440 11.92 17,823 1 4,000 1.23 1,839 839 0.60 gg7 p 2 4,000 2.28 3,409 248 1.13 1,690 0 3 4,000 1.66 2,482 0 0.81 1,211 0 4 4,000 2.18 3,260 0 1.38 2,063 0 5 4,000 3.89 5,816 1,816 1.60 2,392 p 6 4,000 2.63 3,932 1,749 1.51 2,258 0 7 4,000 1.01 1,645 0 0.44 658 0 8 4,000 1.19 1,779 0 0.60 8g7 0 9 4,000 3.15 4,710 710 1.50 2,243 0 10 4,000 2.76 4,157 867 0.87 1,301 0 11 4,000 1.71 2,557 0 0.74 7,106 0 12 4.000 1.24 1,854 0 0.74 1,106 0 8,000 25.04 37,440 11,82 17 823 OV CO(lert7 26 Texas Guide to Rainwater Harvestlng tAINFALL DATA FOR SELECTED COMMUNITIES ACRnSS TFxc This chart contains monthly rainfall data from 40 weather stations across Texas. The statistics are based on 50 years of recorded rainfall, from 1940 through 1990. For each statioq • 0a11iart six monthly precipitation values are given: a°ariira ^ MIN. The minimum recorded occurrence is the lowest recorded rainfall in 50 years. ~~~ ^ 10% The 10%occurrence level indicates that 90%of the ;~ Wr:Mta Falls De xalb• time monthly rainfall is higher. ubanr Gauss xamat ^ 25% The 25% occurrence level indicates that 75% of the •~~7 -Abilene Wealhafw° Longview time monthly rainfall is higher. EI Paso . ~ wmt Mfa;a°aro°esaa . sa° Mgero Lifkin • were ^ 50% The 5D% (median) occurrence level describes ~% Gn~on t ' ~ e monthly rainfall for half the time. 9ate ' uPme ~ela a°m ausri S u ° an ~ n°an,ae ^ AVE. The average mont}ily (mean) occurrence level ~""10ontl •Gor°aks~ factors in precipitation extremes and is higher than the 50% Eagle Pass ~~~~ Galverion (median) data. Got;°~° ~~ ^ MAX. The maximum recorded occurrence is the highest Falfurias recorded mondtly rainfall in 50 years. Refer [o the map below [o see if [here is a data set for r~r~~ your town If you live between weather stations, average grown:v° kwso the monthly predpi[atlon values for the closest town to the north and to the south, since precipitation patterns vt Texas rvn from the north to south/southwest. (See map of Aver- age Annual Precipitation th Texas, page 19.) MONiN MIN. 10% 25% 50% AVE. MAX. MO^TN MIN. 10% 25% 50% AVE. MAX. Abernathy Aekerly January 0.00 O.DO 0.09 0.35 0.57 3.75 January 0.00 0.00 0.00 0.37 0.56 2.17 February 0.00 0.01 0.12 0.45 0.67 2.28 February 0.00 0.00 0.09 0.44 0.63 3.20 Match 0.00 0.01 0.17 0.44 0.72 3.13 Mareh 0.00 0.00 0.00 0.48 0.75 3.91 April 0.00 0.13 0.37 0.88 1.11 3.96 Aprll 0.00 0.00 0.23 0.74 1.14 7.15 May 0.31 0.68 0.98 1.81 2.47 6.32 May 0.00 0.53 I.10 2.09 2.58 12.61 June 0.32 0.52 1.56 2.84 3.03 8.36 June 0.00 0,00 0.67 2.05 2.13 7.22 July 0.00 0.46 1.20' 2.38 2.44 9.68 July 0.00 0.10 0.59 1.79 2.25 8.30 August 0.10 0.45 0.83 1.96 2.34 8.54 August 0.00 0.10 0.60 1.21 1.78 5.53 September 0.05 0.39 0.74 1.81 2.27 6.43 September 0.00 0.00 D.99 1.99 2.60 10.53 October 0.00 0.00 0.28 1.00 1.67 7.41 October 0.00 D.00 0.49 L10 1.67 6.49 November 0.00 0.00 0.05 0.37 0.61 2.08 November 0.00 0.00 0.00 0.20 0.59 2.89 December 0.00 0.01 0.09 0.31 0.57 2.22 December 0.00 0.00 0.01 0.46 0.65 3.84 Abilene Albany January 0.00 0.00 0.10 0.79 0.98 4.29 January 0.00 O.DD 0.11 0.87 1.27 8.06 Fehruary 0.02 0.10 0.35 1.02 1.08 3.57 February 0.15 0.32 0.60 1.01 1.54 6.51 Match 0.02 0.13 0.41 0.79 1.08 5.08 March 0.06 0.15 0.51 0.99 1.42 4.31 AprO 0.00 0.44 0.97 1.87 2.10 6.76 Aprll 0.00 0.58 1.11 2.16 2.58 10.12 May 0.14 0.70 ].44 2.98 3.36 13.11 May 0.24 1.22 2.20 3.58 3.94 10.46 June 0.00 D.35 1.46 2.19 2.60 9.55 June 0.06 0.32 1.18 2.26 2.87 9.42 July 0.00 0.23 0.66 ].71 2.16 7.11 July 0.00 0.12 0.66 1.79 2.26 11.52 August 0.00 0.34 0.74 1.60 2.31 8.18 August 0.11 0.36 0.71 1.41 1.99 6.53 September 0.00 0.50 1.23 2.31 2.79 10.97 September 0.00 0.22 1.62 2.69 3.35 13.40 October 0.00 0.35 1.01 2.08 2.5] 10.64 October 0.00 0.23 0.89 2.24 2.74 1.01 November 0.00 0.00 0.33 0.76 1.23 4.55 November 0.00 0.00 0.36 0.61 1.43 6.07 December 0.00 0.01 0.18 0.74 1.05 6.22 December 0.01 0.07 0.32 1.12 1.42 8.62 27 Rainfall Dana tm Selected Communitles Aanss Texas MONTH MIN. te% 25% 50% AVE. MAX. MONTH MIN. 10% 25% 50% AVE. MAX. A1Ptne Bakersfield January 0.00 0.01 0.13 0.45 0.54 1.82 January 0.00 0.00 0.02 0.31 0.61 4 Z4 February 0.00 0.00 0.03 0.29 0.47 3.04 Febntary 0.00 0.00 0.10 0.40 0.62 . 4.33 March 0.00 0.00 0.03 0.18 0.35 1.66 Match 0.00 0.00 0.02 0.22 0.42 1 83 Aprll 0.00 0.01 0.07 0.25 0.51 3.60 April 0.00 0.00 0.11 D.54 0.82 . 3 56 May 0.00 0.18 0.43 I.O6 1.19 3.41 May 0.00 0.43 0.89 1.30 1.76 . 4.56 June 0.00 0.41 0.89 1.76 2.04 6.93 June 0.00 0.00 0.18 1.20 1.40 6 00 1u1y 0.05 0.60 1.39 Z.fi6 2.93 9.30 July 0.00 0.03 0.14 0.81 1.21 . 6.23 August 0.05 0.84 1.52 2.27 2.64 8.15 August 0.00 0.03 0.40 1.17 1.46 4.73 September 0.01 0.49 1.00 2.21 2.61 11.08 September 0.05 0.22 0.60 1.64 2.49 23 41 October 0.00 0.11 0.28 0.98 1.28 4.39 October 0.00 0.12 0.32 1.38 1.83 . 13 30 November 0.00 0.00 0.00 0.37 0.47 3.19 November 0.00 0.00 O.OD 0.35 0.57 . 2 61 December 0.00 0.00 0.09 0.28 0.52 2.56 December 0.00 0.00 D.00 023 0.54 . 2.92 Amarillo gty~ January 0.00 0.00 0.11 0.42 0.53 2.30 January 0.00 0.02 0.17 0.71 ].13 6 36 February 0.00 0.03 0.20 0.46 0.55 1.76 February 0.09 0.34 0.70 1.33 1.57 . 5 19 Match 0.00 0.02 0.26 0.59 0.88 3.93 March 0.00 0.11 0.39 0.81 1.19 . 3 44 April 0.00 0.19 0.40 0.85 1.03 2.75 April 0.26 0.52 I.O8 1.68 2.13 . 6 45 May 0.01 0.74 1.4D 2.47 2.69 9.76 May 0.11 1.36 1.90 3.31 3.69 . 7 88 June 0.00 1.00 1.70 3.15 3.44 10.62 June 0.00 0.42 0.81 1.89 2.60 . 8 24 July 0.11 0.79 1.46 2.50 2.77 7.50 July 0.00 0.02 0.17 1.15 1.96 . 13.99 August 0.26 1.20 1.68 2.87 2.99 7.45 August 0.07 0.26 0.63 1.34 2.08 11 12 September 0.02 0.31 0.66 1.59 1.84 4.95 September 0.00 0.57 1.41 2.55 3.19 . 10 41 October 0.00 0.12 0.45 0.99 1.34 4.78 October 0.01 0.18 0.64 1.76 2.47 . 7 68 November 0.00 O.DO 0.14 0.39 0.60 2.23 November 0.00 0.12 0.40 1.10 1.28 . 3 77 December 0.00 0.02 0.15 0.27 0.52 4.46 December 0.00 0.05 0.14 0.76 1.29 . 8.16 Anahuac Brownsville January 0.63 1.15 2.12 4.33 4.09 10.02 January 0.00 0.13 0.36 1.07 1.37 4 74 February 0.00 0.90 1.77 2.81 3.36 10.93 February 0.00 0.05 0.35 1.00 1.43 . 10 21 March 0.05 0.59 1.20 2.03 2.90 8.34 Match 0.00 0.01 0.11 0.33 0.60 . 3 44 April 0.09 0.86 2.02 2.97 3.84 12.53 April 0.00 0.00 0.23 0.88 1.65 . 10 33 May 0.62 1.11 1.89 3.79 4.53 IO.DO May 0.00 0.25 1.14 1.95 2.50 . 9 05 June 0.26 0.77 1.82 3.55 5.16 20.25 June 0.00 0.06 1.34 2.20 2.80 . 8 45 July 0.39 1.69 2.82 4.43 4.59 13.32 July 0.00 0.10 0.31 1.06 1.63 . 9 35 August 0.30 1.76 2.57 3.08 4.68 17.15 August 0.00 0.12 0.88 2.10 2 52 . 9 47 September 0.05 0.76 2.32 5.45 5.51 16.44 September 0.05 ].43 2.79 4.71 . 5.35 . 20 09 OUOber 0.00 0.23 1.33 3.19 4.05 19.02 October 0.33 0.63 1.26 2.79 3.17 . 17 03 November 0.50 1.21 2.10 3.44 4.10 10.74 November 0.00 0.09 0.51 0.86 1.48 . 7 63 December 0.63 1.56 2.13 3.39 4.33 13.46 December 0.00 0.02 0.14 0.71 1.09 . 3.91 Austin Cameron January 0.02 0.35 0.60 1.23 1.79 9.14 January 0.00 0.55 0.96 1.73 2.28 8 94 February 0.23 0.59 1.13 2.28 2.40 6.48 February 0.44 0.85 1.63 2.84 2.78 . 7 38 Matth 0.00 0.25 0.81 1.66 1.84 5.97 Match 0.07 0.48 0.96 1.74 2.20 . 7 29 April 0.03 0.53 1.38 2.18 2.89 9.85 April 0.01 1.31 1.62 2.53 3.54 . 11 58 May 0.77 1.17 1.60 3.89 4.40 9.90 May 0.57 0.88 2.96 4.12 4.36 . 9 74 June 0.00 0.66 1.51 2.63 3.41 14.87 June 0.00 0.46 1.13 2.59 3.01 . 8 6] July 0.00 0.11 0.44 1.10 1.75 10.50 July 0.00 0.00 0.20 1.01 1.50 . 9 23 August 0.00 0.25 0.60 1.19 2.03 8.89 August 0.00 0.08 0.36 1.21 1 66 . 5 71 September 0.09 D.80 1.50 3.15 3.22 7.41 September 0.01 0.72 1.17 3.26 . 3.54. . 12 49 October 0.00 0.56 0.87 2.78 3.50 12.25 October 0.00 0.58 1.32 2.40 3.54 . 11 49 November O.DO 0.32 0.74 1.71 2.05 7.28 November O.OD 0.58 I.IB 2.51 2.73 . 7 60 December 0.00 0.32 0.74 1.24 2.18 14.05 December 0.16 0.51 1.16 2.06 2.64 . 11.64 28 Texas Cnide to Rainwater Harwsdng VII. COST CONSIDERATIONS rainwater harvesting system designed as an integrated component of a new con- struction project is generally more cost- effective than retrofitting a system onto an existing building. This is because many of the shared costs (roof and gutters) can be designed to optimize system performance, and the investment can be amortized over time. As described above, a system can be designed as afull-service or supple- mentalwater source, each having specific costs and paybacks. While costs for the same system are equivalent regardless of whether there is access to a municipal water supply, payback (the amount of time it takes to recoup the investment relative to dollars saved) varies depending on other available water supply options. For example, based on cur- rent water rates, payback on a system where the only option is drilling a well is better than if municipal water supply is available, since the cost of drilling a well and associated annual mainte- nance and treatment costs are often higher than annual costs of a municipal water supply. Other variables which affect system economics include choice of tank and filtration. In general, maximizing storage capacity and m;nim;Tng wateruse through conservation and reuse are important rules to keep in mind. softened and treated to remove dissolved minerals, and the rainwater system is owner-built, which is a viable option for people with available time and basic skills. Factoring in the full costs of drilling and operating a well are necessary to understand com- parative costs. For example, costs of drilling a well vary depending on soil type and water availability, and range from about $6.00 to $15.00 per linear foot of depth. In addition, wells require a pump and possibly a water softener and filter, depending on water quality. Monthly costs including operations, maintenance, appliance replacement, are estimated to be as much as $120. In addition, reliance on well water has the potential uncertainties of long term water supply and water quality. And, if salt is added to well water, a related environmental cost is the resulting negative impact on soil quality, which can make the soil sterile. Around the state, dty-supplied water is relatively inexpensive, though does not always reflect the "full" cost of water including costs of heatment and pumping. For new construction, many cities require a tap to be installed before a Certificate of Occu- pancy will be issued. The tap fee is generally in the range of $1,500 to $2,900, depending on rates for particular cities. Because of these factors, the return of afull-service rainwater harvesting system where For buildings outside a municipal water service city water is available is rarely less than 30 years and area, rainwater harvesting systems designed to fulfill all water requirements can be as costly and frequently more expensive, than the cost of drilling a conventional well. However, there is evidence that with careful planning and design, the cost of a rainwater system can be less than the cost of a well in many cases - especially if the well water must be can be as high as 90 years, assuming about present values for municipal water and approximate con- struction costs of $1.00 per gallon of collection capacity for a rainwater harvesting system. Although difficult to quantify, an important con- sideration for some people when comparing op- tions is the value of water quality, which varies 33 ' ~ r tremendously depending on source. Some rain- water harvesters in Texas believe rainwater to be the highest quality water available, and therefore worth the added expense to harvest. Understanding water quality relative to avail- able water sources may be an important consider- ation for you in determining what water source to rely on. Hardness and Mgh mineral content in some parts of Texas make muniapal and private well water less desirable because of deposits that build- up on pipes and appliances, poor taste, and pos- siblenegative health effects. Therefore, the value of the rainwater due to its high quality may offset the added expense if the alternative is high mineral content city-water, especially if additional costs of bottled water for cooking and drinking, a water softener, and increased soap use are factored in. In parts of the state where city-supplied water is satisfactory, a rainwater system as a supplemental water source may be most practical. For example, a Cast Coralderatlons system sized just for drinking and cooking, or just for garden irrigation, ran be significantly smaller than afull-service system, but provide the benefits that have particulaz value to the user. Conventional fmancing for stand alone rain- water harvesting systems has been provided for just a few new homes in Texas. While this has not become standard practice, such precedents will help to educate the fmantial community of the viability of rainwater harvesting. However, until this practice is better understood, appraisers may underestimate the value of a rainwater system, and insurance underwriters may require aback-up wa- ter source such as an on-demand supply contract with a local water hauler. ®The term "stand alone system" refers to rainwater harvesting systems that do not have municipal or well water back-up. 34 Texas Cuide to Rainwater Harvestlng VIII. CODE AND SAFETY ISSUES he Texas Natural Resource Conservation Commission (TNRCC) regulates munia- pal and well water, not rainwater. The Texas Department of Health (TDH) regu- lates mosquito hazazds and greywater. Check with local authorides since no agency authorizes or in- spects private rainwater collection systems. The Texas Plumbing Code does not allow doubletrench- ingwastewater and potable water lines. In Austin, for example, an airgap wider than the munidpal line must exist between the public water and rain- water to keep the rainwater from entering the supply outlet The State of Ohio Department of Health and the State of Virginia Bureau of Sewage and Water Ser- vices regulate rainwater systems. Since the State of Texas does not presently inspect or enfon:e any guidelines regarding captured rainfall, you may want to consider some specifications from these other states when designing your system. ^ A astern may not be located closer than 50 feet from a source of contamination, such as a septic tank ^ A astem must be located on a grade lower than the roof washer to ensure that it can fill completely. ^ A rainwater system must include installation of an overflow pipe which empties into anon-flooding area. ^ In]ets to asterns must be designed to dissipate pressure of influent stream and minimize the stirring of any settled solids. ^ An above-ground roof washer or filtering device shall be provided on all cisterns. ^ The water intake for a pump in a astern shall be attached to a flotation device and be located a minimum of 4 inches below the surface of the water. ^ Overflow from rainwater systems cannot flow into wastewater systems. ^ Cisterns shall be accessible for cleaning. ^ All openings into the cistern shall be screened. ^ Cisterns cannot be relied upon to provide potable water without adequate treatment consisting of roofwashing and continuous disinfection. 35 Rainwater Harvesting List SAS WATER DEVELOPMENT BOARD Page 1 of 4 List of Rainwater Harvesting Providers The following is a list provided for informational purposes only and inclusion in the list is in no way an endorsement of that firm or its products. Rainwater Company ?.O. Box 1360 3lanco, Texas 78606 830)833-4334 systems, installation, ion, treatment testing supplies, zne and fiberglass Barley & Pfeiffer Architects - Peter Pfeiffer 1800 West 6th Street Austin, Texas 78703 ;512) 476-8580 System design, design/build, ~owerbird Construction '.O. Box 698 )ripping Springs, Texas 78620 512) 419-4555 %erocement tanks, systems John Dorn Tank Building, Inc. '.O. Box 150 Vidor, Texas 77670-0150 409) 769-5129 3olted, galvanized, coated --- ~-- 3arrel City USA 3401 South 1st Street Austin, Texas 78748 512)282-1328 2ecycled SS-gallon drums Bell Landscape & O. Box 16159 istin, Texas 78716 12)899-8888 'sign, intallation, systems, Designers -Ashley 16 Remschel Ave. errville, Texas 78028 X30) 257-7400 onsultation and desk ed Ewald, Inc. O. Box 519 arnes City, Texas 78118 00) 242-3524 reinforced tanks Rainwater Harvesting List & Ranch Service Supply O. Box 10165 m Antonio, Texas 78210 00) 292-0007 ~ncrete tanks, roof washers, andmark Structures, Inc. 1665 Harmond Rd. t. Worth, Texas 76177 (817) 439-8888 or (800) 888- 6816 steel tanks reload, Inc. 710 LBJ Freeway, Suite 140 -allas, Texas 75240 300)645-3195 'oncrete tanks Waterworks -Charles '.O. Box 972 gipping Springs, Texas 78620 512)858-7020 design, installation, systems Tank Town -Richard Heinichen, Mayor 1212 Quail Ridge Dripping Springs, Texas 78620 (512) 894-0861 Tanks, complete systems, how- & F Manufacturing O. Box 578, Highway 290 Jiddings, Texas 78942 800) 237-5791 Fiberglass Tanloc Membranes Industrial Vinyl t. 4, 5203 W. 42nd Street dessa, Texas 79764 X15) 333-3055 VC bladders Sweetwater Filtration (Rainsoft Products) 1321 Rutherford Ln. Ste. 180 Austin, Texas 78753 (512) 837-2488 or (888) 877- rainwater Collection Over 'exas - TX Lic. #6047 000 Dry Hole Drive ;yle, Texas 78640 300)222-3614 systems, service, 'ripple S Feed 111 Highway 290 West gipping Springs, Texas X8620 512)894-0344 'olvethvlene tanks Yage 1 of 4 Rainwater Harvesting List ~ Page 3 of 4 Water Filtration Company 1205 Gilman Water Works of Texas -Jess arietta, Ohio 45750 Reich (800) 733-6953 or (740) 373- 2206 Matterhorn Lane 6953 ustin, Texas 78704 0o wahers, f floating filters, (512)326-4636 more ainwater systems nviro Jet Inc. P.O.Box 11219 GR Simmons, Inc. Waco, Texas 76716 3803 Willaims Dr. (800) 880-4659 or (817) 666- Georgetown, Texas 78628 8181 (512) 869-1175 endrix Tanks Rainwater Systems -John 1002 East Avenue J. Coats Lampasas, Texas 76550 3203 S. Lamar (512) 556-4734 ustin, Texas 78704 (512)442-7841 Sustainable Homesteads ustin Pump & Supply P.O. Box 2669 3803 Todd Lane Wimberley, Texas 78676 ustin, Texas 78744 (512)832-0757 (512)442-2348 olyethylene tanks, pumps If your company is directly involved in rainwater collection systems, service, supplies, or design and you wish to have your company listed, please write, fax or e- mail: Send the information to the attention of the Conservation Section TEXAS WATER DEVELOPMENT BOARD 2G. C-C.! 13x1 • 1707 fJ. ~.GFdGkC SS P!~EfuE • F.USTiN, T:~: 78717-3.31 fSl2) au3-18x7 • Fur.: f51U i75-?DSO Last updated: 09/07/99 by Max Castaneda mcastanena twdb state tx us (512)463-7982 Alternative Sources Paae Conservation Main Pa P "T[x7ilD it r~mn Dnrro Appendix .. ~ . APPENDIX GLOSSARY air gap: a vertical space between a water or drain line and the Oood ]eve] of a receptacle used to prevent backflow or siphonage from the receptacle in the event of negafive pressure or vacuum. aquifer. an underground waterway that is replenished 6y precipitatlon. backflow: flow of water in a pipe or water line in a direction opposite to normal flow. backflow preven[er. a device or system installed in a water line to stop backflow from a nonpotable source. blackwa[er, as defined in Texas, the wastewater from toilets and kitchen sinks. buffer. to shift pH to a specific value. building footprint the area of a building on the ground. cistern: an above or below ground tank used to store water, generally made of galvanized metal, fiberglass, ferrocement or concrete. duinfearon: a process in which pathogenic (disease produc- ing) bacteria are killed by use of ctilorine or physical pro- cesses. diverter. a mechanism designed to divert the fast Flush rainwater from entering the cistem. erosion: the loss of topsoil that occurs as a result of ran-off. filtration: the process of separating particles of 2 microns or larger in diameter from water by means of a porous substance such as a permeable fabric or layers of inert material housed in a media filter or removahle rarrridge filter. fast flush: generally the first 10 gallons of rainwater per 1,000 square feet of roof surface that is diverted due to potential for contamination. flow rate: the quantity of water which passes a given point in a specified unit of time, expressed in gallons per minute. forcebreakec an extension of the fill pipe to a point 1" above the bottom of the cistem, which dissipates the pressure of incoming rainwater and thus minimizes the stirring of settled solids. greywater. as defined in Texas, the wastewater from residen- tial appliances or fixtures except toilets and kitchen sinks. groundwater. water found below ground that has seeped there through spaces in soil and geologic formations. hardness: a characterisdc of groundwater due to the presence of dissolved calcium and magnesium which is responsible for most wale fotmadon in pipes and water heaters. hydrologic cycle: the continual exchange of water from the atmmphere to [he land and oceans and back again. leaf screen: a mesh installed over gutters and entry points to downspouts [o prevent leaves and other debris from clogging [he flow of rainwater. micron: a linear measure equal to one millionth of a meter, or .00003937 inch. nonpotable water. water intended for non-human con- sumption purposes, such as irrigadon, toile[ flushing, and dishwashing. pH: a logarithmic scale of values of 0 to 14 that measure of hydrogen ion concentration in water which determines whether the water is neutral (pH 7), acidic(pH 0-7) or basic (pH 7-14). pathogen: an organism which may cause disease, potable water. water which is suitable and safe for human consumption. pressure tank: a component of a plumbing system that provides the constant level of water pressure necessary for the proper operation of plumbing fixtures and appliances. rainwater harvesting; the principle of collecting and using precipitation fiom a catchment surface. roof washer. a device used to divert the fast flush rainwater from entering a cistern. rnn-off farming: the agricultural application of harvested rainwater involving a system of terraces that directs the rainwater from higher to lower elevafions. sedimentation: the process in which solid suspended par- ticles settle out (sink to the bottom) of water, frequendy after the particles have coagulated. total dissolved solids: a measure of the mineral content of water supplies. xeriscape: a landscape practice which specifies regionally- adapted, drought-resistant plants and other water-conserving techniques. 59 ` Texas Guide to Rainwater Harvesting ABBREVIATIONS FDA Food & Dmg Administradon mg/L milligrams/Liter TDS Total dissolved solids THMs Trihalomethanes psi pounds per square inch PVC Polyvinylchloride TDH Texas Department of Health REFERENCES BOOKS Barnett, Dianna Lopez with William D. Browning, APrimer on Sustainable Building, Rocky Mountain Institute, Snowmass, CO, 1995. An overview of sustainable building practices covering a wide range of green building topics, including economics, design features, site selection and development, transportation, energy and water conserva- tion, indoor air quality. Campbell, Stu, Home Water Supply: How to Find, Filter, Store, and Conserve I~ Garden Way, Charlotte, VT, 1983. City of Austin, Sustainable Building Sourcebaok, City of Aus- tin Environmental and Conservation Services Departrnent, Austin, TX, 1995. A periodically updated and comprehen- sive guidebook of sustainable building materials and meth- ods, including a section on rainwater harvesting. Also available digitally at www.greenbuildeccom. Darrow, Ken and Mike Saxenian, Appropriate Technology Sourcebnok A Guide to Ptactlpl Books for tillage and Small Community Technology, Volunteers in Asia, Stanford, CA, 1989. An annotated bibliography of the "best books" on small-scale technologies applicable to developing coun- tries; includes several references [o small-scale rainwater catchment systems and cistern constmction. Frasier, Gary W„ Editor, Water Harvestng Symposium Pro- ceedt~ngs, Phoenix, Arizona, March 26-28, 1974, U.S. Water Conservation Laboratory ARS, USDA, 4331 East Broadway, Phoenix, AZ 85040 Harrison, Joseph F., and Wes McGowan, WQA Glossary of Terms, Water Quality Association, Lisle, IL, 1993. Milne, Murat' Residentla/ Water Re-Use, Water Resources Center, The Regents of the University of California, Davis, Report No. 46, ISSN 0575-4968, 1979. A delightful, well- illustrated, thorough book on residential water-reuse meth- ods, prepared for the California Water Resources Center. The book explains ways to collect, store, treat, and distrib- ute greywater, rainwater, groundwater, and surface water N residential contexts, and includes units of measure and an annotated bibliography. TNRCC Texas Natural Resource Conservation Commission TWDB Teams Water Development Board Mollison, Bill, PermacW[ure: A Designers' Manual, Tagari, Tygalum, Australia 1988. Natonal Academy of Sciences, More Water (or Arid lands. Nafiona] Academy of Sciences, Washingron, D.C., ]974. As noted by Murray Milne, "Fascinating and valuable, espe- cially good chap[ers~on Rainwater Harvesting, reuse of water, wells, innovative irrigation." National Park Service, Guiding Principles of Sustainable Dr sign, Government Printing Office, Denver, CO, 1993. Guide- lines designed to enhance the environmental integrity of design and construction projects undertaken by the Na- tional Park Service; also applicable to other comparable public and private sector initiaflves. Pacey Arnold and Adrian Cullis, Rainwater Harvesting: The Collection o(RainhB and Runo((in Rural Areas, Intermediate Technology Publiradons, London, 1986. An historical over- view of rainwater harvesting and an overview of designing and cnnswcting rainwater collection systems, with an emphasis on rural applications and developing countries. Rea] Goods, Alternative Energy Sourcebook 1990, Real Goods Trading Company, Ukiah, CA, 1989. One of the most comprehensive references for off-the-grid living, this sourcebook is updated and Combines product purchasing information with short, concise treatises on a variety of appropriate technologies, including on-sitewa[er supply. Speidel, David H., Lon C. Ruesdisili and Allen F. Agnew, Perspectives on Water Uses and Abuses, Oxford University Press, New York, 1988. Spence, Clark C., The Rainmakers American Pluviculture to World War II, University of Nebraska Press, Lincoln, NE, 1980. Steadman, Philip, Energy, Environment and Building, Cam- bridge University Press, New York, 1975. Includes a short section on rainwater collectoq reuse design proposals, and local water collection with examples. Stewart, John Cary, Drinking Water Hazards: Haw to Know i(There Are Toxic Chemicals in Your Water and What to Do 55 References rf7here Are, Envirogmphirs, Himm, OH, 1990. A discussion of common water pollutants, what standard laboratory tests identify, how to interpret test reults, and home treat- ment options should contamination be identified through testiing. Texas Center for Policy Studies, Texas Environmental Alma- nac, Texas Center for Policy Studies, Austin, TX, 1995. An excellent resource on facts and figures relating to the Texas environment, including a comprehensive analysis of water resources. Water Quality Association, Water Fi)oatlon for Point-of--Use Application, Water Quality Association, Lisle, IL, 1993. Watt, S.B., Ferrocement Tanks and Their Constrvtroon, Interme- diate Technology Development Group, London, 1978. BOOKLETS, BROCHURES, PAMPHLETS Institute for Rural Water, "Cons[mcting, Operating and Maintaining Roof Catchments," Water for the World, Tech- nical Note No. R.W.S.LC.H., U.S.D.A., 1982. IrugaHon & Water Management Institute, "A Bibliography of Water Harvesting/Runoff Farming & Small Scale Water Management Systems," 1st Edition, College of Agriculture, University of Auzona, Turson, AZ 85721. Jade Mountain, "Water Storage," Jade Mountain, P.O. Box 4616, Boulder, CO 80306, 1/8D0-442-1972 Schatzberg, Donnie, Build Your Own Ferro-Cement Water Tank, Precious Mountain, 1221 Neistnth Road, Cazadero, CA 95421, 1979. An instruction manual on building ferro-cement water tanks, wutten for do-i[-yourselfers, in- cluding mnsttucdon steps, material requirements, and siz- ing calculatlons. Selfredge, Tom & Frank Pearson, "Residential and Insdtu- tional Rainwater Collection Systems for Irugation on Monterrey Peninsula," Sanitary Engineeung & Environ- mental Health Research Laboratory University of Califor- nia, Berkeley, CA 97404. State of California, Department of Water Resources, Cap- tured Rainfall: Small-Scale Water Supply Systems, Bulletin 213, May 198]. Symons, fames M., Plain Talk About Drinking Water: Answers to ]01 Questlons About the Water You Drink, New York, Ameuran Water Works Association, 1992. Tank Town, 1996 Catalogue, Tank Town, 1212 QuaB Ridge, Dupping Springs, TX 78620, 512-894-0861. Texas Water Development Board, Texas Water Facts, TWDB 91-0166, Austin, TX, 1991. Valenfine, R.L., et.al. Rainwater Collection System Charac[eus- da and System Design. Sanitary Engineering Resea¢h Labo- ratory College of Engineering and School of Public Health, U.C. Berkeley UCB-SEAL Report N77-4, Berkeley, CA, Octo- 56 ber 1977. Reviews several rainwater system performance models, based on case studies of 13 representadve sites in California. Water Filtration Company Alternative Water Sourzrs far Rural Areas Using Ponds, Ickes, Springs, and Rainwater Cis- terns, Marietta, OH, 1990. PAPERS . Chin, Salwyn S., "Water Supply Potenfial for Asphalt Lined Catchment near Holualoa, Hawaii," Contributions to Hy- drology of USA, GB701.W3 1809 (USGS Library), 1964. Diamant, B.Z. "Roof catchments: The appropriate safe dunking water technology for developing countries," Pro- ceedings of the Internatloanl Conference on Rainwater Cistern Systems, June 1982. Edwards, D. and K. Keller, "Workshop Design for Rainwa- ter Roof Catchment Systems," Water and Sanitatlon for Health (WASH) Project, Tech Report No. 27. Fok, Y.S., E.T. Murabayashi & R.H.L. Fong. "Rainwater Roof-Catchment Cistern System for Residential Water Sup- ply," Third World Congress on Water Resources Pmmtdings, Vol. N, pp. 1712-1716, Intemationa] Water Resources Asso- ciation, Mexico City, Mexico, Apra 23-27, 1979. Fok, Y.S., "Integrating Rain Water Cisterns with Public Water Supply Systems„ Proncedings of the Intematlonal Con- ference on Rain Water Cistern Systems, U.S. Department of Inteuor, Water & Technology, University of Hawaii at Manoa, WR.R.C., pp. 317-322, 1982. Jenkins, D., and E Pearson, "Feasibility of Rainwater Col- lecdon Systems in California," National Technical Informa- tion Service, California Water Resources Center Project, UCAL-WRC-W-539, August 1978. This paper highlights some of [he limitadons related [o on-site rainwater harvest- ing systems, especially cost and annual fluctuation in pre- cipitation. Johnston, G.A. and M.F. Patrons, "An Assessment of Using Collected Rainwater to Reduce Potable Water Consump- tion for Residential Iriga[ion," Proceedings of the 95th An- nual Canferenre of the Wes[em Canada Water and Wastewater Assodadon, Saskatoon, Saskatchewan, 1993. Karpiscak, Martin M., et.al., "Casa Del Agua: A Community Water Conservation and Evaluation Project," University of Auwna, Tucson, AZ 1986. Keller, Ken[, "Rainwater Harvesting for Domestic Water Supply in Developing Countues: A Literature Survey" U.S. Agency for Intemationa] Development. Water and Sanita- tionfor Health Project, 1611 Kent Stmet, Room 1002, Arling- ton, Virginia 22209, Order No. WASH C252. This paper focuses on family and small-scale community water supply systems, with technical notes regarding planning and con- struction of rooftop catchment designs. Texas Guide to Rainwater Harvesting Krishna, J. Hari, "Rainwater Catchment for Future Genera- tions," PosbConference Proceedings of the 5th Interna- tional Conference on Rain Water Cistern Systems, National Taiwan Ocean University, Keelung, Taiwan, 1991. Ibid. "Rainwater Catchment Systems in the Virgin Islands," IRCSA Regional Conference, 1992. Lye, Dennis, "Microbiology of Rainwater Cistern Systems: A Review," Journal of Environmental Spence and Health, A27(8), pages 2123-2166, 1992. This paper provides infor- mation about the estimated inventory of over 253,000 indi- vidually maintained rainwater systems currendy in use in the United Slates. Parsons, M. Fraser, P.E., Gordon Johnston, P.E., Albert Kwan, P.E., "Rain Catchment for Lawns and Gardens - A Strategy to Reduce Peak Water Demands," Proceedings of Conserv '93, American Water Works Association, 1993. This paper describes a project undertaken by the Conservation Section of Edmonton Public Works to evaluate the econom- ics, reliability, and suitability of rain catchment as asupple- mental souroe of irrigation water, pardculazly as a means to offset summer peak water demand. Pearson, Frank at al. (1979). Storage requirements for do- mestic rainwater collection systems in California. Proceed- ings of AWWA 1979 Annual Conference-Our Job, All the Water You Need, (pages 671-697). San Francisco, CA. Perrens, S.J~, "Collection and Storage Strategies for Domes- tic Rainwater Supply," Proceedings of the Hydrology Sympo- sium, Insdtu[e of Engineers, Armidale, New South Wales, Australia, IEA Report 75/3, pp. 168-172, 1975. Quek, U., and J. Forster, "Trace Metals in Roof Run-off, Water, Air and SoU Pollution," WAPLAC, vol. 68, no. 3-4, p. 373-89, June 1993. Ree, W.D., "Rooftop Runoff for Water Supply," Agricultural Reseamh Service, USDA Report ARS-S-133, Washington, D.C., 1976. Schiller, E.J. and B.G. Latham, "A Generalized Method for Designing Rainwater Collectors," Canadian Wafer Resources Journal, Uol. 17, No. 2, 1992. Schiller, E.J., "Rooftop Rainwater Catchment Systems for Drinking Water Supply," Water Supply and Sanitatlon in Developing Countries, Ann Arbor Science, 1982. Woods, Paul, Ph.D., and Iftekhar Choudhury, "Colonias Water Development," Texas A & M University, College Staton, TX, 199E Identities rainwater harvesting as a viable self-help method to mitigate the water supply problems in the Texas colonias. Ibid., "The Potential for Residential Rainwater Catchment and Grey Water Reuse in the United States," Texas A & M University, College Station, TX, ]991. Provides a geographic basis for determining viability of rainwater harvesting in Texas, and includes sizing calculations and a schematic of the water-supply-system components. Ibid., "Potential for Residential Use of Rainwater in Texas," Texas A & M University, College Station, TX, 1991. Yaziz, MI, et al, "Variations in Rainwater Quality from Roof Catchments," Water Research WATRAG, vol. 23, no. 6, June 1989: p. 761-5. MAGAZINE ARTICLES Ionides, Michael. "Shall We Run Short of Water?" Ebstlcs, Vol. 43, No. 254, January 1977. Krehbiel, Edwin P., "you're sure of a water supply with a cistern patio," Popular Sdence, April 1979, pp. 125-126. Michaelides, G, and R.J Young, "Rainwater Harvesting for Domestic Use in Rural Areas," Eldstlcs, No. 303, Novem- ber/December 1983. This article idenflBes advantages of small scale water systems, such as individual household water cisterns, over massive systems serving large cities, as away to fulfill water requirements for all. "Up on the Roof," Rodale's New Shelter, April ] 980, pp. 36-37 VIDEOS Rainwater Collection Systems, distributed by Gardening Naturally Productions, sponsored in part by Red Ewald, Inc., Karnes City, TX 78118, produced by Morris Media Associates, Austin, TX, 1992 ORGANIZATIONS American Rainwater Catchment Systems Associaton, P.0. Box 685283, Austin, TX 78768-5283 Ameriran Water Works Association, 6666 West Quincy Avenue, Denver, CO, 80235 Center for Maximum Potential Building Systems, 6604 F.M. 969, Austin, Texas 78724. (512) 928-4786. Water Quality Association, 4151 Naperville Road, Lisle, IL 60532 COMPUTER PROGRAMS Raincatch, developed by Commonwealth Scientific and In- dustrial Research Organization, Division of Tropical Crops and Pastures, Townsfille, Australia: enables a given roof and tank to be quickly tested over the entire period of historical rainfaO records by computer, and can fmd the most economic means of achieving a desired reliability or the greatest reliability for a given cos[, from any starting point, with or without rationing. Program initially developed for an Aus- tralian project in Africa, but can be applied anywhere that rainfall consumption, and cost data are available. 57 References °' ' ~ Rainx2[er System Simulator (RainSim) is a spreadsheet pro- gram developed 6y Rain Hawes[, Inc. (now Sustainable Homesteads), that simulates the performance of a rainwa- ter collecdon system. For every month of the simulation, it subtracts [he water that is used and adds in any rainwater that was collected. The amount of water remaining in the cistern a[ the end of the month is output to a graph. The program uses historical minfal] records from the National Weather Service tecotrls for the years 1955-1984 recorded in Austin, Texas. A total of 100 years' rainfall data may be added to the program. The following values are manipulated for simulation: ^ the size of the collection area in square feet ^ the number of gallons [ha[ will be used each month ^ [he total size of storage capacity in gallons ^ the amount of water in storage at the beginning of the simulation, in gallons ^ the amount, ff any, of water that will be put into storage if it is empty. A companion program, RainCalc, calculates water produc- tion and peak now rate based on the conection area and peak design minfal] rates to be expected in this area once every 10 years. RainCa/c is used to properly design the collection plumbing system to catch al] rainfall flowing off the roof without losing any to system back-up. RESOURCES- a list of Rainwater design, construction and equipment firms is available upon request. If you want your firm listed; send information to Conservation, Texas Water Development Board, P.O. Box 13231, Austin, Texas 78711-3231 58 COMPLIMENTS OF UGRA