Georgia Rainwater Harvesting Manual

GeorgiaRainwaterHarvestingGuidelines In accordance with Appendix I!Rainwater Recycling Systems of the 2009 Georgia Amendments to the 2006 International Plumbing Code

Wednesday, April 1, 2009 DRAFT COPY GA RAINWATER GUIDELINES MANUAL 5 Georgia Rainwater Harvesting Guidelines PREFACEThe Georgia Rainwater Harvesting Guidelines are intended to assist all parties involved in the design,construction, inspection and maintenance of rainwater harvesting systems and to help successfully complywith Appendix I-Rainwater Recycling Systems of the 2009 Georgia Amendments to the 2006 InternationalPlumbing Code (IPC). The parties mentioned above include owners, building officials, design professionalsand contractors. This consensus document is the product of the parties listed below:Guideline Committee Members:Frances Carpenter, chair Bill GuinadeMax Rietschier Marvin RichardsBill Morris Tom CartyErnest U. Earn Bob FreemanDavid Freedman Phillip T. McCreanor, Ph.D.Randy Starr Eddie Van GiesenChris Kumnick Shawn HatleyRyan Meres Frank HenningGreg JeffersThe Guidelines Committee wishes to take this opportunity to express our sincere appreciation to thoseindividuals who donated their time and effort to the development and production of this document. Specialthanks goes out to Eddie Van Giesen and Frances Carpenter for their efforts as principal authors and editorsof this document.Disclaimer and Notice:While the information presented in these guidelines is believed to be correct, the parties involved assume noresponsibility for its accuracy or for the opinions expressed herein. The material presented in this publicationis not considered Code and should only be used for reference and guidance in complying with therequirements of Appendix I Rain Water Recycling Systems. All rainwater harvesting systems shall complywith the Georgia State Minimum Standard Plumbing Code (2006 IPC with Georgia Amendments) and allother applicable State Minimum Standard Codes for construction. Users of information from this publicationassume all liability arising from such use.The 2009 Georgia Amendments to the International Plumbing Code which contain Appendix I Rain WaterRecycling Systems can be downloaded from the Department of Community Affairs website at the followinglink: http://www.dca.ga.gov/development/ConstructionCodes/programs/codeAmendments.asp April 2, 2009 DRAFT for Public Comment 1 of 58 Wednesday, April 1, 2009 DRAFT COPY

Wednesday, April 1, 2009 DRAFT COPY GA RAINWATER GUIDELINES MANUAL 7 Georgia Rainwater Harvesting Guidelines TABLE OF CONTENTSFigure 4-12 Corrugated steel tank................................................................................. 11 CHAPTER 1 .................................................................................................... 1 GENERAL INFORMATION .............................................................................1 1.1 Purpose ................................................................................................... 1 1.2 ARCSA .....................................................................................................1 CHAPTER 2 .................................................................................................... 3 INTRODUCTION TO RAINWATER HARVESTING ........................................ 3 2.1 The Big Picture ....................................................................................... 3 2.2 History ..................................................................................................... 5 .................................................................. 6 2.3 Current Usage of Rainwater .............................................................................7 2.4 Response to Drought ................................................................................................. 10 2.5 Benefits .................................................................. 10 2.6 Economics and Feasibility ........................................................................................ 11 2.7 In conclusion .................................................................................................. 12 CHAPTER 3 SYSTEM SIZING AND WATER BALANCING ............................................. 12 3.1 Water Conservation .............................................................................. 12 3.2 Stormwater Runoff Reduction ............................................................. 13 3.3 Green Building ...................................................................................... 14 3.4 System Sizing ........................................................................................ 15 3.5 How Much Water Can Be Captured? ................................................... 16 3.6 Calculating Storage Capacity .............................................................. 18 3.7 Water Conservation Supplemental to Other Resources .................. 20 3.8 Summary ............................................................................................... 20 April 2, 2009 DRAFT for Public Comment 2 of 58 Wednesday, April 1, 2009 DRAFT COPY

8 Wednesday, April 1, 2009 DRAFT COPY GEORGIA RAINWATER GUIDELINES MANUAL Georgia Rainwater Harvesting Guidelines CHAPTER 4 .................................................................................................. 21 HARVESTING COMPONENTS....................................................................21 4.1 Introduction and Fundamental Elements ........................................... 21 4.2 The Catchment Surface ........................................................................ 24 -Metal Roof ................................................................................................... 24 -Clay/Concrete and Tile Roof ..................................................................... 24 -Composite or Asphalt Shingle .................................................................. 25 -Wood Shingle, Tar, and Gravel ................................................................. 25 ............................................................................................................ 25 -Slate ......................................................................................... 25 -Vinyl/rubberized ..................................................................... 25 4.3 Gutters and Downspouts ................................................................... 26 -Gutter Sizing and Installation .................................................................................. 26 4.4 Primary Filtration ...............................................................................................27 -Leaf Screens ......................................................................................27 -Downspout Filters -Strainer Baskets .........................................................................................27 -First-Flush Diverters .................................................................................. 28 4.5 Storage ................................................................................................... 29 -Tank Siting .................................................................................................. 29 4.6 Tank Materials ...................................................................................... 33 -Rain Barrel .................................................................................................. 33 -Above Ground Polypropylene .................................................................. 33 -Fiberglass ................................................................................................... 34 -Below Ground Polypropylene ................................................................... 34 -Metal ............................................................................................................ 36 April 2, 2009 DRAFT for Public Comment 3 of 58 Wednesday, April 1, 2009 DRAFT COPY

Wednesday, April 1, 2009 DRAFT COPY GA RAINWATER GUIDELINES MANUAL 9 Georgia Rainwater Harvesting Guidelines -Concrete ..................................................................................................... 36 -Wood ........................................................................................................... 37 4.7 Pumps and Controls ............................................................................ 37 4.8 Treatment and Disinfection .................................................................. 39 CHAPTER 5 .................................................................................................. 40 WATER QUALITY AND TREATMENT COMPONENTS.............................. 40 5.1 Introduction ........................................................................................... 40 5.2 Factors Affecting the Quality of Harvested Rainwater ...................... 40 .................42 5.3 Water Treatment For Non-potable Outdoor Use Systems ....................42 5.4 Water Treatment For Non-potable Indoor Use Systems 5.5 Additional Requirements for Use as Cooling Tower Make Up Water 6 4 ......................................................................................... 46 5.6 Conclusions .................................................................................................. 47 GLOSSARY ................................................................................................... 51 References ...................................................................................................... 52 WebsitesApril 2, 2009 DRAFT for Public Comment 4 of 58 Wednesday, April 1, 2009 DRAFT COPY

Wednesday, April 1, 2009 DRAFT COPY GA RAINWATER GUIDELINES MANUAL 11 Georgia Rainwater Harvesting GuidelinesList of FiguresFigure 2.1 Statewide Water Level Restrictions................................................................. 4Figure 2.2 Lake Lanier Level Diagram.............................................................................. 6Figure 2.3 Aerial Photo of Lake Lanier 2007.................................................................... 7Figure 2.4 ! Basic Hydrological Cycle.................................................................................8Figure 2.5 The Hydro-Illogical Cycle................................................................................ 9Figure 3.1 Catchment area of typical roofs...................................................................... 16Figure 4.1 Diagram of above ground cistern................................................................... 21Figure 4.2 Diagram of below ground cistern................................................................... 22Figure 4.3 Rainwater Harvesting Flow Chart.................................................................... 23Figure 4.7 Calming Inlet.................................................................................................. 26Figure 4.5 Downspout filter............................................................................................. 27Figure 4.6 Strainer Basket................................................................................................ 27Figure 4.7 First Flush Diverter.......................................................................................... 28Figure 4.8 Wooden tank.................................................................................................. 30Figure 4.9 Schematic for 350 gallon Rain barrel........................................................ 32Figure 4.10 75 gallon Rain barrel.................................................................................... 33Figure 4.11 Plastic polypropylene tanks.......................................................................... 33Figure 4.12 Below ground Fiberglass tanks..................................................................... 34Figure 4.13 Below ground polypropylene tanks.............................................................. 35Figure 4-14 Corrugated steel tank................................................................................... 36Figure 4.15 Wooden aboveground tank.......................................................................... 37Figure 4.16 Submersible on demand pump with floating suction .................................. 38Figure 4.17 On demand external pump........................................................................... 38Figure 5.1 First flush diverter............................................................................................ 41 April 2, 2009 DRAFT for Public Comment 5 of 58 Wednesday, April 1, 2009 DRAFT COPY

Wednesday, April 1, 2009 DRAFT COPY GA RAINWATER GUIDELINES MANUAL 13 Georgia Rainwater Harvesting GuidelinesList of TablesTable 3.1 Percentage of water uses................................................................................... 13Table 3.2 Major GA Cities Annual Precipitation 1971-2000 - 30 year average (inches).... 17Table 3.3 Table for rainwater potential collection from roof surfaces............................. 18Table 4.1 Storage tank materials descriptions.................................................................. 31Table 4.2 Tank volume for a given height and diameter (1,000 GAl units)....................... 32Table 4.3 Typical minimum requirements of commons fixtures in water-harvesting........ 37Table 5.1 Treatment Techniques...................................................................................... 45 April 2, 2009 DRAFT for Public Comment 6 of 58 Wednesday, April 1, 2009 DRAFT COPY

Wednesday, April 1, 2009 DRAFT COPY GA RAINWATER GUIDELINES MANUAL 1 Georgia Rainwater Harvesting GuidelinesCHAPTER 1GENERAL INFORMATION1.1 PurposeRainwater, for purposes of this document, is Installers and the general public are advised towater collected from roof surfaces during rain comply with local and state codes.events. This water is then stored in tanks or On January 1, 2009, Appendix I Rainwatercisterns for later use. Potential uses include Recycling Systems of the Georgia 2009indoor non-potable applications (toilet Amendments to the 2006 Internationalflushing) and outdoor non-potable applications Plumbing Code took effect allowing rainwater(irrigation systems, hose bibs, etc). Rainwater harvesting in certain applications throughoutHarvesting (RWH) in its essence is the the state. The guidelines presented in thiscollection, conveyance and storage of document (Georgia Rainwater Harvestingrainwater. Rainwater collected from roofs is Guidelines) will assist regulators, rainwaternot recycled water, nor is it gray water. It systems designers and end users in rainwateris fresh water that is in abundant supply, and is harvesting best management practices. Thegenerally undervalued in the United States. water available from such systems will offer high quality water to supplement utility-Rainwater Harvesting Systems (RWHS) for provided water for approved non-potable endpurposes of this document, are defined as uses.systems that collect, store and use precipitationcollected from rooftops or other man made,above ground collection surfaces. 1.2 ARCSAThe use of rainwater harvesting systems in The American Rainwater Catchment SystemsGeorgia can serve to supplement non-potable Association (ARCSA) is one of the bestwater demands while maintaining and sources of information about rainwater harvesting. ARCSA (www.arcsa.org), anenhancing the quality of the environment. affiliate of the International RainwaterThese guidelines are intended to be consistentwith, and complimentary to, the requirements Catchment Systems Association (IRCSA,of the Georgias 2009 Amendments to the 2006 www.ircsa.org ) is an organization formed inInternational Plumbing Code, National Institute 1994 by Dr. Hari J. Krishna in Austin, Texas.of Health, and local Boards of Health. ARCSAs primary mission is to promote rainwater catchment systems in the Americas April 2, 2009 DRAFT for Public Comment 7 of 58 Wednesday, April 1, 2009 DRAFT COPY

2 Wednesday, April 1, 2009 DRAFT COPY GEORGIA RAINWATER GUIDELINES MANUAL Georgia Rainwater Harvesting Guidelinesthrough educational opportunities, theexchange of information at the ARCSA websiteand regularly scheduled workshops andcourses.ARCSA has published guidelines for rainwaterharvesting systems, and is currently writingnational standards for the rainwater harvestingindustry, both of which are available on theirwebsite. Currently Rainwater CatchmentDesign and Installation Standards are beingdeveloped by a joint effort of ARCSA and theAmerican Society of Plumbing Engineers(ASPE). The purpose of these standards is toassist engineers, designers, plumbers, builders/developers, local government, and end users insuccessfully implementing rainwater catchmentsystems. These standards will apply to newrainwater catchment installations, as well asalterations, additions, maintenance and repairsto existing systems.Rainwater harvesting systems can range from asimple 55 gallon rain barrel to a complexmultimillion-gallon cistern with electronicpumps and controls. It is important to evaluateexisting site conditions of the project to ensurecompliance with state and local requirementsduring the planning phase.To assist in understanding the terminology ofRWH, a glossary of commonly used terms isprovided at the end of this document. April 2, 2009 DRAFT for Public Comment 8 of 58 Wednesday, April 1, 2009 DRAFT COPY

Wednesday, April 1, 2009 DRAFT COPY GA RAINWATER GUIDELINES MANUAL 3 Georgia Rainwater Harvesting GuidelinesCHAPTER 2INTRODUCTION TORAINWATER HARVESTING2.1 The Big PictureThe Earths surface is 75 percent covered by The United States population more than tripledwater; only 3 percent of this water is suitable from 76 million people in 1900 to 281 millionfor human consumption. Of that 3 percent most people in 2000. The population growth of 32.7is either locked in polar caps or hidden beyond million people in the 1990s was the largestthe practical reach of commercial technologies. numerical increase of any decade in U.S.Less than 1 percent of our water is found in history (Hobbs, Frank and Nicole Stoops, U.S. Censuslakes, rivers, and approachable undergroundaquifers. In addition, all freshwater sources are The city of Tucson, Arizona, onderived from either rainfall or snowmelt. Thiswater then makes its way into the ground, or it Tuesday became the firstflows into inland freshwater bodies or the municipality in the country toocean. Fresh water is a diminishing limited require developers of commercialresource, and though we cannot increase the properties to harvest rainwaterEarths supply of water, we can manage what for landscaping. The new water-supplies we have more effectively. saving measure - approved by aGlobal consumption of water has been unanimous vote by the Citydoubling every 20 years, more than twice the Council -- mandates that newrate of human population growth. We are using developments meet 50 percent ofwater as if it is an infinite resource, but its not. their landscaping waterWe are in fact depleting our planets usable requirements by capturingwater supply. Shrinking fresh water suppliespresent the most urgent and potentially rainwater. The new rule goes intocatastrophic environmental problem today effect June 1, 2010. http://worldwide (Barlow, 2002). www.biologicaldiversity.org/ news/center/articles/2008/land- letter-10-16-2008.html. April 2, 2009 DRAFT for Public Comment 9 of 58 Wednesday, April 1, 2009 DRAFT COPY

4 Wednesday, April 1, 2009 DRAFT COPY GEORGIA RAINWATER GUIDELINES MANUAL Georgia Rainwater Harvesting Guidelines Figure 2.1 Statewide Water Level RestrictionsBureau, Census 2000 Special Reports, Series CENSR-4, Excluding agriculture, one estimate forDemographic Trends in the 20th Century, U.S. Georgias average daily per-capita waterGovernment Printing Office, Washington, DC, 2002). consumption is estimated at 168 gallonsStatewide (Georgia) public-supply water use compared with a national average of 153has increased steadily since 1980, gallons. Steps need to be taken to ensure thatcorresponding to an increase in population Georgias water supply continues to meet theduring the same period. Water use for public needs of the economy (Dodd, http://supply likely will continue to increase as the www.gppf.org/article.asp?RT=20&p=pub/Water/ envwateruse040528.htm).S t a t e s p o p u l a t i o n g r o w s . ( h t t p : / /ga.water.usgs.gov/pubs/other/ggs-ic106/pdf/ggs- Rainwater harvesting systems address manyic106.pdf). water issues associated with population growth April 2, 2009 DRAFT for Public Comment 10 of 58 Wednesday, April 1, 2009 DRAFT COPY

Wednesday, April 1, 2009 DRAFT COPY GA RAINWATER GUIDELINES MANUAL 5 Georgia Rainwater Harvesting Guidelinesand urban expansion,, such as reduced public and building new pipelines and associatedwater consumption improved stormwater technologies (Texas Manual, 2006).quality and increased soil infiltration.We all use rainwater either directly or Rainwater harvesting can be envisioned asindirectly. Water from a municipal source, an relieving, not replacing, some of the burdenexample of an indirect use of rainwater, comes placed on the existing public utilities especiallyfrom a spring or reservoir fed by rainfall and during times of drought and high demand.snowmelt, the ultimate suppliers of thesesources. Because the water runs across parking 2.2 Historylots and highways, through fields that may The collection and use of rainwater is not new.have been treated by pesticides, down storm Long before centralized water delivery andgutters, and into the lakes and streams, the treatment systems were built, our ancestorsmunicipal water authority has to treat the water knew that access to water was a basic necessitywith chemicals to kill pathogens and correct for for survival. Archeological evidence of RWHpH. Rainwater harvesting, an example of a techniques date back at least 4,000 years. Ruinsdirect use of rainwater, is not exposed to the of cisterns have been found in Israel, believedsame pollutants and therefore does not require to be from 2,000 BC. The concept of rainwaterthe same level of treatment as water which harvesting may date back 6,000 years (Gouldflows overland and underground before its and Nissen-Peterson 1999).collected. Public utilities have the addedburden of maintaining existing supply and In the 20th century, large-scale public waterstormwater infrastructure as well as designing systems were developed in industrialized During a Level 4 drought, virtually all outdoor water use is prohibited. A Level 4 drought is an extreme drought, with lake levels, stream flows and rainfall at or approaching the lowest levels in 100 years. In Georgia, a Level 4 drought was declared in 2007 for the northern third of the state, including the metropolitan Atlanta area. The declaration was made because rainfall in this portion of the state was more than 20 inches below normal (see http://www.caes.uga.edu/topics/disasters/drought/ totalrainfallmap .html) in 2007 and 2008, and stream flows were far below normal across the state. April 2, 2009 DRAFT for Public Comment 11 of 58 Wednesday, April 1, 2009 DRAFT COPY

6 Wednesday, April 1, 2009 DRAFT COPY GEORGIA RAINWATER GUIDELINES MANUAL Georgia Rainwater Harvesting Guidelines Figure 2.2 Lake Lanier Level Diagramcountries and RWH became restricted to IRCSA to promote and advance rainwaterspecialized applications and regions, such as on catchment systems technology.small islands and in semi-arid rural areas of theworld. Law in the U.S. Virgin Islands and 2.3 Current Usage ofmany other Caribbean Islands requires RWHdue to limited fresh water sources. Interest in RainwaterRWH in the United States and around the globe There may be as many as 250,000 RWHhas grown significantly in recent years due to systems in use in the United States (Kincade,d r o u g h t s a n d w a t e r s h o r t a g e s . RW H 2007). Texas, Virginia, Oregon, the state ofassociations are forming in countries all over Washington, and other states have developedthe world and many are now joining together in guidelines for designing and installing April 2, 2009 DRAFT for Public Comment 12 of 58 Wednesday, April 1, 2009 DRAFT COPY

Wednesday, April 1, 2009 DRAFT COPY GA RAINWATER GUIDELINES MANUAL 7 Georgia Rainwater Harvesting Guidelinesrainwater harvesting systems. In Hawaii, up to now source their water from rainwater tanks.60,000 people depend on RWH systems for Countries such as Germany, Australia, Newtheir water needs (Macomber, 2001). In India, Zealand, Great Britain, Sri Lanka, India,since June 2001, the Ministry of Urban affairs Pakistan and othersand Poverty Alleviation has made rainwater are considerably farther along in theirharvesting mandatory in all new buildings with understanding and regulation of the use ofa roof area of more than 100 square meters and rainwater. In some instances both local andin all plots with an area of more than 1,000 national authorities insist on designed andsquare meters, that are being developed (http:// installed rainwater catchment systemsw w w. r a i n w a t e r h a r v e s t i n g . o r g / U r b a n / integrated into new developments.Legislation.htm). In the United States somemunicipalities require RWH systems in new 2.4 Response to Droughtdevelopments. Tucson, Arizona recently passed By August 2000, 36 percent of the Unitedthe nations first rainwater harvesting States was in severe to extreme drought,ordinance for commercial properties. Currently leading to widespread wildfires and othermore than 10 percent of New Zealanders rely drought-related damages (Natl Oceanic andon rainwater for their drinking needs (Abbott, A tmospheric Administration Climate of 2000 - September, U.S. Drought National Climatic Data Center, 16 October2008). In Australia 17 percent of households Figure 2.3 Aerial Photo of Lake Lanier 2007 April 2, 2009 DRAFT for Public Comment 13 of 58 Wednesday, April 1, 2009 DRAFT COPY

8 Wednesday, April 1, 2009 DRAFT COPY GEORGIA RAINWATER GUIDELINES MANUAL Georgia Rainwater Harvesting Guidelines2000 (National Oceanic and Atmospheric Administration, there will always be a supply of clean water in .2001; U.S. Department of Agriculture, 2000) Georgia and in our region as a whole. Recent drought conditions in the Southeast and in Georgia in particular have triggered manyAccording to David Stookesbury, state municipalities and governing bodies to placeclimatologist for the state of Georgia, the water restrictions on the use of municipal waterperiod between WWII and the late 1970s was ( F i g u r e 2 . 1 , S t a t e w i d e Wa t e r L e v e lan abnormally benign climatic period. Since Restrictions). In some instances outdoorthe late 1970s we returned to a more normal watering has been banned completely. Evenclimate pattern that involves greater year-to- more alarming is the possibility ofyear variability in temperature and rainfall. For implementing contingency plans for prioritizedcity planners, public water authorities and the use of municipal water supplies. RWH hasagriculture industry, this means increased great potential for supplying water for variousdifficulty in planning. uses in the midst of these restrictions.It has generally been taken for granted that Figure 2.4 Basic Hydrological Cycle April 2, 2009 DRAFT for Public Comment 14 of 58 Wednesday, April 1, 2009 DRAFT COPY

Wednesday, April 1, 2009 DRAFT COPY GA RAINWATER GUIDELINES MANUAL 9 Georgia Rainwater Harvesting Guidelines Figure 2.5 The Hydro-Illogical CycleThe city of Atlanta derives most of its water boundary between Georgia and Tennessee hasfrom Lake Lanier. In December 2008, lake been recently disputed over water rights in thelevels were near the all time low (Figure 2.2, Tennessee River. The aerial view of drought-Lake Lanier Level Diagram). As difficult as stricken Lake Lanier (Figure 2.3, Aerial Photothis is to imagine, there is a finite amount of of Lake Lanier, 2007) makes it clear thatwater in the lake. Once the water level goes actions must be taken to address water suppliesbelow the level of the intakes, there is no way in our State.to extract any more water until the lake isreplenished by additional rains, or until the Water conservation is in the minds of many ofintake is lowered, which could require our citizens and policy makers. Unlike otherdredging and large capital outlays. natural disasters, drought does not have a clearly defined beginning and end. As a result,Water rights and water availability are our reaction to drought traditionally has notimportant and relevant topics today. Politics, been timely. It is human nature to think thatindustrial interests, and environmental just because it rained yesterday that the droughtconcerns all play into this picture. The state is over. This is largely due to widespread lack April 2, 2009 DRAFT for Public Comment 15 of 58 Wednesday, April 1, 2009 DRAFT COPY

10 Wednesday, April 1, 2009 DRAFT COPY GEORGIA RAINWATER GUIDELINES MANUAL Georgia Rainwater Harvesting Guidelinesof understanding of the basic hydrological RWH is by nature decentralized andcycle (Figure 2.4, Basic Hydrological Cycle relatively less vulnerable to naturalNational Drought Mitigation Center, disasters than public water supplies.University of Nebraska, Lincoln, Nebraska, Harvested Rainwater is low inUSA). minerals and it is ideal for activities such as car washing. Since itPublic attention tends to wane after significant contains no chlorine, rainwater israin events and sometimes after small ones. also ideal for filling garden pondsThe cartoon in Figure 2.5, The Hydro-Illogical and irrigating sensitive plants.Cycle, cleverly illustrates the point that Widespread adoption of rainwaterappearances can be deceiving. harvesting can increase the efficiency of expensive water2.5 Benefits supply infrastructure.Given the variability in the amounts and timingof rainfall received, collecting water when it 2.6 Economics andcomes in abundance for use at a later time islogical and sustainable. Integrating rainwater Feasibilityharvesting concepts into new construction Municipal water is generally purchased atdesign generally does not present relatively low rates throughout the state.overwhelming problems. Retrofitting most According to EPA region 4 Environmentalbuildings to collect the rainwater that is Finance Center, the median monthly amountordinarily piped away is a relatively simple charged for minimum usage of water is $10.00,procedure. In many cases, the gutters, $20.50 for 6,000 gallons, and $29.50 fordownspouts and pipes are already present on 10,000 gallons. As a point of comparison, athe building. gallon of potable water at a major groceryThe numerous benefits and advantages in retailer is $1.20 per gallon while the medianharvesting rainwater include the following: bill for 6,000 gallons is $0.0034 per gallon Rainwater is free. Although its which is approximately 350 times cheaper initial equipment installation costs (http://www.efc.unc.edu/publications/pdfs/ can be significant, long-term costs GA2007WaterSewerRatesReport.pdf). are workable, given our circumstances. For most Georgians, spending significant Stored rainwater gives its owner amounts of money on a RWH system is low on more independence from the effects the priority list. When calculating the of irregularities of rain events. payback for a residential or commercial rain harvesting system, costing in the thousands of April 2, 2009 DRAFT for Public Comment 16 of 58 Wednesday, April 1, 2009 DRAFT COPY

Wednesday, April 1, 2009 DRAFT COPY GA RAINWATER GUIDELINES MANUAL 11 Georgia Rainwater Harvesting Guidelinesdollars, often the investment cannot be justified pressure on municipal and private waterbased only on the relatively cheap cost of supplies. Understanding how to implementmunicipal water. Perhaps it makes more sense these technologies is key in rainwaterto think in terms of the overall ecological harvesting as a viable safe supplement to abenefit gained from reducing demands on shrinking water supply.public fresh water supplies.For some individuals the satisfaction ofcatching the rain is motivation enough. Freshwater demands from ground sources (wells),both public and private can also be reduced byusing rainwater. It is worth pointing out that insome instances, the only thing preventing theloss of an established landscape during periodsof outdoor watering restrictions is a RWHsystem. For some residents, having the peaceof mind that their new or existing landscapewill survive and thrive is the only motivationneeded to install a RWH system. In the case ofsome businesses in some municipalities in theSoutheastern US, the ability to remain inbusiness has depended on a functioning RWHsystem.2.7 In conclusionWorldwide freshwater shortages clearlyindicate that immediate action must be taken toimplement RWH technologies. RainwaterHarvesting has been practiced since ancienttimes. We know from history that local andregional droughts occur on a regular basisthroughout the world. We also know that manythousands of RWH systems exist throughoutthe US and that when they are properlydesigned and installed they are able to providemany benefits, most immediately to alleviate April 2, 2009 DRAFT for Public Comment 17 of 58 Wednesday, April 1, 2009 DRAFT COPY

12 Wednesday, April 1, 2009 DRAFT COPY GEORGIA RAINWATER GUIDELINES MANUAL Georgia Rainwater Harvesting GuidelinesCHAPTER 3SYSTEM SIZING ANDWATER BALANCINGRWH systems can range from the very simple public commercial buildings, educationalto the very complex. It is absolutely facilities and homes. For example, the Energyfundamental to determine the reasons for Policy Act of 1992 requires that from Januarycollecting rainwater prior to designing any 1994 onward all toilets sold in the Unitedsystem. There are many reasons for wanting to States use no more than 1.6 gallons of waterhave a RWH system; however, three of the per flush, well below the 3.5 gallons per flushmost important reasons are: used by most American toilets (Energy Policy Act of 1992. Public Law 102486, 102nd Congress. Wa t e r c o n s e r v a t i o n a n d Washington, D.C. Oct. 24, 1992 http://www.cepis.ops- supplemental water supply; oms.org/muwww/fulltext/repind48/energy/energy.html). Storm water reduction; and Achieving Green building goals. Georgias average daily per-capita water consumption, excluding agriculture, isExamining these three areas (water estimated at 168 gallons compared with aconservation, stormwater runoff reduction, and national average of 153 gallons. Only oneGreen building) helps focus on the benefits of percent of this water is used for drinkingcollecting rainwater and establishes specific purposes (Benita Dodd, Georgia Public Policyparameters in designing a rainwater system. If Foundation (May 28, 2004), http://www.gppf.org/a project must be 20 percent more water default.asp?pt=news&RT=20). Even during timesefficient or must reduce site runoff by 60 of drought there is plenty of rainfall in Georgiapercent, a specific goal has been established for that can be harvested and used to supplementassistance in determining the type and size of the demands for non-potable purposes such asthe rainwater system required to meet these landscape watering, toilet and urinal flushing,project objectives. and cooling tower makeup. Water used for non-potable purposes does not3.1 Water Conservation require the same level of treatment as waterConservation practices are those that help us that must meet EPA drinking water qualityextend the usefulness of a specific resource. standards. In order to safely serve these needs,Water conservation makes good economic this water must have, however, appropriatesense and is sometimes law for private and quality. See Chapter 5 for more information on water quality. April 2, 2009 DRAFT for Public Comment 18 of 58 Wednesday, April 1, 2009 DRAFT COPY

Wednesday, April 1, 2009 DRAFT COPY GA RAINWATER GUIDELINES MANUAL 13 Georgia Rainwater Harvesting Guidelines USE GALLONS PER % OF DAILY TOTAL CAPITA POTABLE INDOOR USES: Showers 11.6 7% Dishwashers 1 0.60% Baths 1.2 0.80% Faucets 10.9 6.60% Other uses, leaks 11.1 6.70% Subtotal potable indoor uses 35.8 21.70% NON-POTABLE INDOOR USES: Clothes washers(Non permissable per 15 9.10% code in GA) Toilets 18.5 11.20% Subtotal non-potable indoor uses 33.5 20.30% NON-POTABLE OUTDOOR USES 95.7 58% Table 3.1 Percentage of water uses3.2 Stormwater Runoff soak into the ground as close to the location where it falls, is another goal of LID. A RWHReduction system can act as a large sponge, absorbing andLow Impact Development (LID) is a design storing water for later use. The water can thenand site development methodology that allows be released at a slower rate via landscapenewly developed and/or existing sites to watering.hydrologically mimic pre-developmentconditions. For example, if a forested area is Stormwater retention requirements can bedeveloped for commercial purposes, one LID partially achieved by incorporating RWH as angoal would be to mimic some of the integral part of the design (http://hydrological functions of trees and encourage www.lowimpactdevelopment.org/). From 1991 tocleansing and infiltration of site rainwater 2005 the state of Georgia has had an increaserunoff. Capturing rain and encouraging it to of 111% in the amount of impervious surface, April 2, 2009 DRAFT for Public Comment 19 of 58 Wednesday, April 1, 2009 DRAFT COPY

14 Wednesday, April 1, 2009 DRAFT COPY GEORGIA RAINWATER GUIDELINES MANUAL Georgia Rainwater Harvesting Guidelinesincreasing its impervious area from 216,805 3.3 Green Buildingacres to 455,337 acres (Natural Resources Spatial With the growing awareness of the need toAnalysis Laboratory, College of Agricultural and reduce our footprint on the environment, a newEnvironmental Sciences, UGA http://narsal.uga.edu/ movement toward a more conscious,glut/ecoregion.php?ecoregion=5). In urban areas sustainable and wise development has beenacross the state, rain dubbed Green.falls on a roof surface, Many buildingtravels through a gutter/ The National Green Building organizations havepiping network, and Standard offers the following points programs witheventually arrives as for rainwater collection: rating systems forstormwater into a creek new developments,or river. Impervious 801.11 Rainwater collection and homes andsurfaces force water to distribution. commercialflow rapidly through buildings. Thesestormwater systems and (1)Rainwater is collected and rating systems arethus overwhelm creek used: 6 points based inand stream banks, sustainabilitycausing ongoing (2)Rainwater is distributed using a s t a n d a r d s .ecological degradation. renewable energy source or R a i n w a t e r gravity: 2 points harvesting canUnfortunately in some assist in achievingurban environments in Courtesy of NAHB 2009 the desired level ofGeorgia, sewage and (National Association of Home "Green." Forstormwater still flow in example, thethe same pipe networks. Builders) N a t i o n a lDuring particularly w w w. n a h b r c . o r g / t e c h n i c a l / s t a n d a r d s / Association ofheavy rain events, raw gbversion1_chapter08.pdf Home Buildersuntreated sewage may (NAHB) has abe carried directly into program thatcreeks and streams. awards points for integrating a RWH systemHarvesting some of the rainwater before it into the construction of new homes. NAHB,enters the stormwater drainage system can help the International Code Council (ICC) and thereduce peak flow volumes during these rain NAHB Research Center have initiated aevents and therefore lessen the environmental process for the development of an ANSIimpacts of these combined systems. standard for Green home building construction April 2, 2009 DRAFT for Public Comment 20 of 58 Wednesday, April 1, 2009 DRAFT COPY

Wednesday, April 1, 2009 DRAFT COPY GA RAINWATER GUIDELINES MANUAL 15 Georgia Rainwater Harvesting Guidelines Harvested Water (gal) = catchment area (sq.ft.) X depth (in.) X 0.623 (conversion factor) A simple estimate of the number of gallons that can be harvested from a given catchment area after a rainfall event can be determined with the following formula. The total number of gallons harvested is equal to the catchment area (square feet) times the depth of a rainfall (inches) times a conversion factor of 0.623.practices, which is titled The National Green for a total of 41 consecutive dry days, a recordBuilding Standard ( http://www.nahbrc.org/ in the state (http://www.ncdc.noaa.gov/oa/climate/technical/standards/gbinvitation.aspx). extremes/2000/october/octoberext2000.html).Selecting materials for rainwater systems basedon locally available components and equipment Rainfall is fairly evenly distributed throughoutcontaining recycled content may achieve the year in the state of Georgia. This evenfurther credit. distribution enables storage capacity to be somewhat less than in other areas of the3.4 System Sizing country (arid southwestern states) where rainfall occurs more seasonally (longer periodsA basic goal for sizing any rainwater of time between rain events). Storage capacityharvesting system is to balance the volume of needs to be sufficient to store water collectedwater that can be captured and stored (supply), during heavy rain events to last through drycompared to the volume of water used periods. Some residences might be constrained(demand). In order to balance the system, the by the size of the collection surfaces and/or thesupply must equal or exceed the demand. This volume of storage capacity that can be installedis easiest to understand if broken down on a due to space or costs. The following sectionsmonthly basis. describe ways to determine the amount of rainfall, the estimated demand, and how muchIn Georgia, the longest anticipated period storage capacity is needed to provide enoughbetween rain events is normally less than 30 rainwater to meet the demand. The rainfall datadays. However, no measurable rain fell from for selected Georgia cities is found in TableSeptember 25th through November 4th, 2000 3.2, Major Georgia Cities Annual Precipitation. April 2, 2009 DRAFT for Public Comment 21 of 58 Wednesday, April 1, 2009 DRAFT COPY

16 Wednesday, April 1, 2009 DRAFT COPY GEORGIA RAINWATER GUIDELINES MANUAL Georgia Rainwater Harvesting Guidelines Note: It is important to understand that regardless of the pitch, the shape, or the complexity of any roof surface, it is the overall footprint of the building that determines the collection area. (see Figure 3.1)Figure 3.1 Catchment area of typical roofs3.5 How Much Water CanBe Captured? surface is the area covered by collection surface (length times width of the roof fromApproximately 0.62 gallons per square foot of eave to eave and front to rear). Obviously, ifcollection surface per inch of rainfall can be only one side of the structure is guttered, onlycollected during a rain event. Some rainwater the area drained by the gutters is used in theis lost to first flush (see components, see calculation. For commercial buildings refer toglossary), evaporation, splash-out or overshoot the plumbing code for additional sizingfrom the gutters in hard rains, and possible requirements.leaks. Rough collection surfaces are lessefficient at conveying water, as some of the Rainfall Distributionwater captured on porous surfaces tends to be According to the Georgia State Climatologylost to evaporation. A much more in depth Office, average annual rainfall in Georgiaanalysis of how to calculate potential harvested varies from a low of about 40 inches inrainwater is available through the ARCSA Montgomery County to a high of over 80website (http://www.arcsa.org/resources.html) inches in isolated mountainous areas in thein their guidelines publication. northeastern part of the state. If the rainwater harvesting system is intended to be the soleCollection Surface water source for a specific use, the catchmentThe collection surface is the footprint of the area and storage capacity must be sized to meetroof. In other words, regardless of the pitch or the water demand through the longest expectedshape of the roof, the effective collection April 2, 2009 DRAFT for Public Comment 22 of 58 Wednesday, April 1, 2009 DRAFT COPY

Wednesday, April 1, 2009 DRAFT COPY GA RAINWATER GUIDELINES MANUAL 17 Georgia Rainwater Harvesting Guidelines City JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC TOTAL ATLANTA 5.03 4.68 5.38 3.62 3.95 3.63 5.12 3.67 4.09 3.11 4.10 3.82 50.20 ATHENS 4.69 4.39 4.99 3.35 3.86 3.94 4.41 3.78 3.53 3.47 3.71 3.71 47.83 MACON 5.00 4.55 4.90 3.14 2.98 3.54 4.32 3.79 3.26 2.37 3.22 3.93 45.00 COLUMBUS 4.78 4.48 5.75 3.84 3.62 3.51 5.04 3.78 3.07 2.33 3.97 4.40 48.57 SAVANNAH 3.95 2.92 3.64 3.32 3.61 5.49 6.04 7.20 5.08 3.12 2.40 2.81 49.58 AUGUSTA 4.95 4.11 4.61 2.94 3.07 4.09 4.07 4.48 3.59 3.20 2.68 3.14 44.58 VALDOSTA 5.79 4.47 5.30 3.61 3.15 4.91 6.30 5.24 4.11 3.11 3.24 3.83 53.06 Table 3.2 Major GA Cities Annual Precipitation 1971-2000 - 30 year average (inches) NOAA National Weather Service Forecast Office, www.srh.noaa.gov Weather Channel, www.weather.cominterval without rain. If additional water is precipitation ranges from 3.4 inches inrequired, other water sources must be November to 5.3 inches in July. The monthlyconsidered to supplement the collected distribution of rainfall is an important factor torainwater. consider for sizing a system.Some rainfall collected from high-intensity, Monthly Rainfall Estimationshort-duration rain events, may be lost to Rainfall estimates should always be preparedoverflow from storage tanks or splash out from for a specific locale, using the best data thatthe gutters. Since these intense rainfall events apply to that area. Two different estimators ofare considered part of the cumulative annual monthly rainfall are commonly used: averagerainfall, the total available volume of such an rainfall and median rainfall. Taking the sum ofevent is rarely captured. historical rainfall and dividing by the numberAnother consideration is that annual rainfall is of years of recorded data calculates averagenot evenly distributed throughout the twelve annual rainfall. Information on rainfall data ismonths of the year. Statewide average monthly available from numerous public sources, April 2, 2009 DRAFT for Public Comment 23 of 58 Wednesday, April 1, 2009 DRAFT COPY

18 Wednesday, April 1, 2009 DRAFT COPY GEORGIA RAINWATER GUIDELINES MANUAL Georgia Rainwater Harvesting Guidelines Rainfall Area X Gallons/Sq. Total Gallons (in.) (Sq. Ft.) Ft. 1 2,200 0.62 1,364.00 5 2,200 0.62 6,820.00 10 2,200 0.62 13,640.00 40 2,200 0.62 54,560.00 50 2,200 0.62 68,200.00 1 3,500 0.62 2,170.00 5 3,500 0.62 10,850.00 10 3,500 0.62 21,700.00 40 3,500 0.62 86,800.00 50 3,500 0.62 108,500.00 1 5,000 0.62 3,100.00 5 5,000 0.62 15,500.00 10 5,000 0.62 31,000.00 40 5,000 0.62 124,000.00 50 5,000 0.62 155,000.00 Table 3.3 Table for rainwater potential collection from roof surfacesincluding the National Climate Data Center 3.6 Calculating Storagewebsite (NOAA, Climatography of the UnitedStates No. 85, Section 2: Precipitation.NCDC: Capacity* National Climatic Data Center (NCDC).* Once the potential for rainfall capture volumeMedian rainfall is the amount of rainfall that is known from rainfall data and catchmentoccurs in the midpoint of all historic rainfall area, the next step is to calculate storagetotals for any given month. In other words, capacity. The decision of whether rainwaterhistorically for the month in question, half of will be used for irrigation, non-potablethe time the rainfall was less than the median domestic use, or both, will factor into howand half of the time rainfall was more than the much water will be used, thus dictating watermedian. demand. April 2, 2009 DRAFT for Public Comment 24 of 58 Wednesday, April 1, 2009 DRAFT COPY

Wednesday, April 1, 2009 DRAFT COPY GA RAINWATER GUIDELINES MANUAL 19 Georgia Rainwater Harvesting Guidelines American Water Works (AWWA) ResearchIf a rainwater harvesting system is to be the Foundation. Of this amount, 42 percent is usedsole water supply for a set of specific uses, indoors, and the remaining 58 percent is usedoverbuilding ensures a safety margin. If budget outdoors. By far the largest percentage ofconstraints do not allow the user to install as indoor water use occurs in the bathroom formuch storage capacity as a sizing method toilet flushing (18.5 gal/person/day) andindicates, it is important to provide an area showering (11.6 gal/person/day). Clotheswhere additional tanks or cisterns can be washers were the second largest water usersinstalled at a later date when finances permit (15 gal/person/day).(Texas Manual, 2006). A simple method for most residences of estimating outdoor irrigation demand isMonthly Demand and Supply analyzing the water bill and comparing waterOne method of determining the feasibility of a usage between the summer and winter months.proposed system is the monthly water balance If water is used for landscape and gardening,method. This method of calculation is similar there will typically be a spike in volume used.to maintaining a monthly checkbook balance. The difference between the summer and winterStarting with an assumed volume of water months will typically be the monthly outdooralready in the tanks, the volume captured each usage. It is shocking to many people when theymonth is added to the previous balance and the discover the vast volume of water that is usedmonthly demand is subtracted. The initial to water lawns.volume of water in the tanks would beprovided by hauling or capturing water prior to Estimating Indoor Water Demandwithdrawing water from the system. Data and Currently the only approved application ofcalculations can be entered on an electronic rainwater in Georgia for indoor purposes arespreadsheet to enable the user to compare toilet and urinal flushing and cooling towerdifferent variables of catchment area and make-up. Although a number of states havestorage. It is suggested that perspective system approved rainwater for use in automatic clothesowners experiment with different variables of washers (washing machines), this is notstorage capacity and, if applicable, catchment permissible in Georgia.surface to find the desired level of comfort andaffordability for catchment size and storage Most American families flush the toilet ancapacity. average of 4 times per day per person. Calculating 1.6 gallons per flush, a family ofEstimating Demand four will use approximately 25.6 gallons perNorth American households use approximately day or a total of 768 gallons per month. If toilet146,000 gal of water annually, according to the flushing will be the sole usage of rainwater for April 2, 2009 DRAFT for Public Comment 25 of 58 Wednesday, April 1, 2009 DRAFT COPY

20 Wednesday, April 1, 2009 DRAFT COPY GEORGIA RAINWATER GUIDELINES MANUAL Georgia Rainwater Harvesting Guidelinesa household, then planning for 30 days withminimal or no rain, would require a storagetank of at least 768 gallons, or the next closestsize (AWWA http://www.cepis.ops-oms.org/muwww/fulltext/repind48/energy/energy.html).3.7 Water ConservationSupplemental to OtherResourcesIt is impossible to separate water conservationfrom system sizing, because the water demanddetermines the system size. Consciouslyconserving water (water-conserving plumbingfixtures, shorter showers, less outdoorirrigation, etc.) decreases the total demand.This results in more efficient use of ourresources and enables us to do more with whatwe already have. For information on residentialwater efficiency, visit the Water Saver Homew e b s i t e ( w w w. h 2 o u s e . o rg ) , a v i r t u a lencyclopedia of water-saving tips, andAWWAs drinktap.org consumer website.3.8 SummaryRainfall events are complicated and an indepthunderstanding of local rainfall is imperative.Those comtemplating designing or installing aRWH system should have an adequate amountof rainfall data, in order to properly size theirsystem (ARCSA GUIDE 2009, Chapter 8). April 2, 2009 DRAFT for Public Comment 26 of 58 Wednesday, April 1, 2009 DRAFT COPY

Wednesday, April 1, 2009 DRAFT COPY GA RAINWATER GUIDELINES MANUAL 21 Georgia Rainwater Harvesting GuidelinesCHAPTER 4HARVESTINGCOMPONENTS4.1 Introduction andFundamental ElementsRainwater harvesting is the capture, diversion, installing a RWH (See figure 4-3, Rainwaterand storage of rainwater for a number of Harvesting Flow Chart).different purposes including landscapeirrigation, non-potable domestic use, aquifer Rainwater systems are available in manyrecharge, and storm water abatement. configurations. Some have below groundUnderstanding how the fundamental storage tanks, above ground tanks, indoorcomponents of a rainwater system work is controls, and some have outdoor controls.crucial when contemplating designing or Figures 4.1 and 4.2 illustrate the primary Figure 4.1 Diagram of above ground cistern April 2, 2009 DRAFT for Public Comment 27 of 58 Wednesday, April 1, 2009 DRAFT COPY

22 Wednesday, April 1, 2009 DRAFT COPY GEORGIA RAINWATER GUIDELINES MANUAL Georgia Rainwater Harvesting Guidelines Figure 4.2 Diagram of below ground cisterncomponents of each type. If the end use isindoors for toilet and urinal flushing, or for Gutters and downspouts: conduits thatcooling tower make-up, treatment components channel water from the roof to the tank.are included as well. Downspout filtration, leaf screens, first-flush diverters, and roof washers: components thatMany factors influence component selection remove debris and dust from the capturedwhen designing or selecting the right rainwater rainwater before it goes to the tank.system for a specific end use application. Storage: one or more storage tanks, alsoGutters, downspouts, buried utilities, soil types, called cisterns.soil depths, slopes, site drainage, existing Pumps and controls: devices such as levelplumbing, electricity, diversion of overflows, indicators, makeup water supplies, back flowlocal restrictions, neighborhood covenants, and preventers and or air gaps.neighbors are some of the many items that Treatment and disinfection: for non-potabledeserve attention when siting RWH systems. indoor systems, filters and other methods toRegardless of the complexity of the system, make the water suitable for use in toiletrainwater harvesting systems are comprised of flushing, urinal flushing and as cooling towersix basic elements: make-up. April 2, 2009 DRAFT for Public Comment 28 of 58 Wednesday, April 1, 2009 DRAFT COPY

Wednesday, April 1, 2009 DRAFT COPY GA RAINWATER GUIDELINES MANUAL 23 Georgia Rainwater Harvesting Guidelines RAINWATER HARVESTING FLOW CHART Catchment Surface First ush Inlet Filtration Calming Inlet Back ow Prevention Storage Make up supply Vector Overow Municipal or well Prevention Air Gap Distribution Pumps, controls, etc Filtration Indoor Use Outdoor Use Disinfection Sediment Evaporative Toilets and Outdoor Cooling Urinals Irrigation, Hose bib Figure 4.3 Rainwater Harvesting Flow ChartApril 2, 2009 DRAFT for Public Comment 29 of 58 Wednesday, April 1, 2009 DRAFT COPY

24 Wednesday, April 1, 2009 DRAFT COPY GEORGIA RAINWATER GUIDELINES MANUAL Georgia Rainwater Harvesting Guidelines4.2 The CatchmentSurfaceThe roof of a building or house for purposes of Condensatethis document is the only choice for the While technically not originatingcatchment surface. Water quality from different from a roof surface, condensateroof catchment surfaces is a function of the from air-conditioningtype of roof material, climatic conditions, andthe surrounding environment (Vasudevan, (dehumidification) units2002). Common sense should prevail in collectively represents adeciding whether or not to collect water from a significant source of water in bothparticular surface. Care should be taken inconsidering how certain roofing materials that residential and commercialcome in direct contact with rainwater affect its applications. The amount of waterquality. Once again, the end use will ultimately that can be collected from anydetermine the viability of a given surface. The given indoor environment variesmajor roof surface types commonly found inGeorgia are listed below. greatly, depending on seasonal climatic conditions, HVAC-Metal Roof equipment and building size. FiveThe surface texture affects the quantity of to twenty-five gallons per day canrainwater that can be collected from a given be collected from many singleroof, the smoother the better (Texas Manual,2006). Powder coated steel is one of the best family residences. Significantlysurfaces to consider. It is very smooth and larger volumes can be collected inwater sheds off it easily during rain events. In commercial applications. Thisaddition, it resists corrosion for extended condensate water can be routedperiods of time. Although relatively moreexpensive than other roof materials, metal either by gravity flow, or with theroofs will outperform most other types over aid of a condensate sump pumptime. directly to the rainwater storage tank.-Clay/Concrete and Tile RoofClay and concrete tiles are both porous. Thesematerials contribute to as much as a 10 percent April 2, 2009 DRAFT for Public Comment 30 of 58 Wednesday, April 1, 2009 DRAFT COPY

Wednesday, April 1, 2009 DRAFT COPY GA RAINWATER GUIDELINES MANUAL 25 Georgia Rainwater Harvesting Guidelinesloss due to texture, inefficient flow, or -Slateevaporation. To reduce water loss, tiles can be Slates smoothness makes it ideal for apainted or coated with a sealant. There is some catchment surface. However, costchance of toxins leaching from the tile sealant consideration may preclude its use.or paint, but this roof surface is safer whencoated with a special sealant or paint to prevent -Vinyl/rubberizedbacterial growth on porous materials. The There are many new roofing materials on thepotential for chemical leaching should be market today primarily used in commercialconsidered if the water will be used for construction. These materials typically havelivestock, fish ponds, or other end uses with thermally or chemically welded seams. Checkspecial water quality considerations (Texas with the roofing material manufacturer forManual, 2006). suitability as a collection surface.-Composite or Asphalt ShingleThe vast majority of residential roof surfaces in 4.3 Gutters andthe United States are made of composite Downspoutsasphalt shingles. For applications discussed in Rood gutters direct the flow of rainwaterthis guide, i.e., non-potable indoor use and running off the eaves of a building. Someoutdoor irrigation, there is little evidence tosuggest serious detrimental water quality gutter installers can provide continuous orimpacts resulting from rainwater from this type seamless gutters. The most common materials for gutters and downspouts are half-roundof surface. Cistern water should be protected PVC, vinyl, and seamless aluminum.from asphalt shingle grit granules and be Regardless of material, other necessaryscreened by a fine downspout filter. components in addition to the horizontal gutters are the drop outlet, which routes water-Wood Shingle, Tar, and Gravel from the gutters downward through theThese roofing materials are increasingly rare in downspout pipe. Whenever possible, fit thenew construction, and the water harvested from downspout pipe snugly to the side of the house.this type of surfaces can contain certain If this is not possible then simply make surecontaminants that may limit its use, due to that the pipe is stable and is firmly connectedleaching of some chemical compounds (Texas to the inlet of the tank using rubber grummets.Manual, 2006). Avoid downspouts/pipes installations that could be easily knocked out of position. Sound building and construction practices should prevail. Additional components include the April 2, 2009 DRAFT for Public Comment 31 of 58 Wednesday, April 1, 2009 DRAFT COPY

26 Wednesday, April 1, 2009 DRAFT COPY GEORGIA RAINWATER GUIDELINES MANUAL Georgia Rainwater Harvesting Guidelines concentrates rainfall runoff from two roof planes before the collected rain reaches a A calming inlet is designed to gutter. Depending on the size of roof area mix the relativelly more terminating in a roof valley, the slope of the anaerobic water at the bottom of the tank with the more roof, and the intensity of rainfall, the portion of oxygenated water closer to the gutter located where the valley water leaves the surface of the tank. This is eave of the roof may not be able to capture all installed at the end of the inlet the water at that point. This can result in pipe and rests on the bottom of excessive spillage or overrunning. Therefore the tank. consider installing an overrun dam to minimize water lost at these valley points during heavy rain events (Texas Manual, 2006). Other factors that may result in over running of gutters include an inadequate number of downspouts, excessively long roof distances from ridge to eave, step roof slopes, and inadequate gutter maintenance. Variables such as these make any gutter sizing rule-of-thumb difficult to apply. Consult your gutter supplier/ Figure 4.4 Calming Inlet installer about your situation with special attention to determine where excessive splash-hardware, brackets, and straps to fasten the out may occur (Texas Manual, 2006).gutters and downspout to the fascia and thewall, and finally to the storage tank itself. Gutters should be installed with a slope(Texas Manual, 2006). towards the downspout. Common sense building should prevail whenever modifying or installing a new roof gutter system.-Gutter Sizing and InstallationAlways check with the local building authorityas to compliance with local codes and 4.4 Primary Filtrationordinances. It is important to consider that To remove debris that gathers on the catchmentmany roofs consist of one or more roof surface, and assure high quality water, somevalleys. A roof valley occurs where two roof filtration is necessary. Some of the many typesplanes meet. This is most common and easy to of filters are shown below.visualize when considering a house with anL or T configuration. A roof valley April 2, 2009 DRAFT for Public Comment 32 of 58 Wednesday, April 1, 2009 DRAFT COPY

Wednesday, April 1, 2009 DRAFT COPY GA RAINWATER GUIDELINES MANUAL 27 Georgia Rainwater Harvesting Guidelines -Downspout Filters The funnel-type downspout filter is typically made of PVC and fitted with an aluminum or stainless steel screen (see Figure 4.5). This type of filter offers the advantage of easy accessibility for cleaning. The funnel is cut into the downspout pipe at the same height or slightly higher than the highest water level in the storage tank. Care must be taken to have the filter high enough to prevent contamination from dogs, but low enough not to discourage the owner/operator from maintaining and cleaning the filter on a regular basis. Figure 4.5

Georgia Rainwater Harvesting Manual

Design

basic hydrological cycle

georgias average daily

rainwater recycling systems

rainwater harvesting systems

rainwater harvesting system

rainwater catchment systems

rainwater potential collection

process water pump