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Rainwater 201: The Next Level of Rainwater Harvesting

For homeowners, building professionals and educators already familiar with the basic concepts of water conservation, especially rainwater harvesting, this workshop discusses advanced topics such as system design, water use offsets and non-irrigation applications such as potable and toilet flushing. Regulatory "red tape" is also discussed, including permitting, building codes, treatment standards, etc.

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Rainwater 201: The Next Level of Rainwater Harvesting

  1. 1. RAINWATER 201:<br />The Next Level of Rainwater Harvesting<br />Brian Gregson<br />Rainwater Catchment Systems Accredited Professional<br />Tri-County Extension Services<br />Brooker Creek Preserve<br />February 2nd, 2011<br />
  2. 2. Outline<br />INTRODUCTION<br />OVERVIEW<br />Why harvest rainwater?<br />Applications<br />DESIGN CONSIDERATIONS<br />ANATOMY 101<br />Potable vs. non-potable<br />Reliability<br />COST<br />REGULATORY CONSIDERATIONS<br /><br />
  3. 3. Who we are<br />Irrigation Contractor: PCCLB 10280<br />Specializing in highly efficient water-conservation solutions<br />Drip/micro irrigation, landscape drainage<br />RAINWATER HARVESTING<br />FIRSTS:<br />ARCSA AP in State of FL<br />Permitted RHS in St. Pete<br />Potable RHS in St. Pete<br />Potable RHS in Tampa<br />Permitted greywater(??) in Tampa<br /><br />
  4. 4. Why harvest rainwater?<br />Preserve potable water for drinking and indoor uses<br />Stormwater management<br />L.I.D.<br />Contribute to responsible growth<br />Larger volume = $$$$<br /><br />
  5. 5. The PROBLEM:<br />Population growth = greater demand on resources (power, water, etc)<br />Reduced reliance on “traditional” groundwater/surface water<br />Sinkholes??<br />Pollution??<br />Greater reliance on “innovative” water supplies (e.g. desalination)<br />RHS reduces demand on blended resources<br /><br />
  6. 6. Rainwater Harvesting:A Sustainable Option<br /><br />Source:<br />
  7. 7. Residential Home, <br />St. Petersburg, FL<br />CISTERN INFO<br />Size:<br />Water Source:<br />Use:<br />1,000 gallons<br />Rainwater<br />Irrigation<br /><br />FIRST SYSTEM PERMITTED AND APPROVED IN ST. PETE!<br />
  8. 8. Florida House Learning Center<br />Sarasota, FL<br />CISTERN INFO<br />Qty/Size:<br />Water Source:<br />Use:<br />Type:<br />Two 2,500 gallon cisterns<br />Rainwater<br />Flushing in water closets,<br />Irrigation, clothes washing<br /><ul><li>East cistern constructed of sprayed lightweight concrete (similar to swimming pools) with a fiberglass-coated liner and a metal roof. </li></ul>• West cistern constructed of concrete block reinforced with poured cores with a liner of flexible, waterproof, acrylic coating and a metal roof. <br /><br /><br />
  9. 9. LEED Elementary School Remodel, St. Petersburg, FL<br /><br />Project Owner:<br />Project Type:<br />CISTERN INFO<br />Size:<br />Water Source:<br />Use:<br />Jordan Park Elementary<br />Institutional<br />2x 2,500 gallons<br />Rainwater<br />Toilet Flushing<br />RAINWATER SERVICES FIRST BELOW-GROUND<br />
  10. 10. Residential – Potable (Laundry) St. Petersburg, FL<br />Project Owner:<br />Project Type:<br />CISTERN INFO<br />Size:<br />Water Source:<br />Use:<br />Private<br />Potable indoor use<br />2x 550 gallons<br />Rainwater<br />Toilets/Laundry<br />ST. PETE’S FIRST POTABLE SYSTEM<br /><br />
  11. 11. Luxury Waterfront – Toilets/Irrigation; St. Petersburg,FL<br />Project Owner:<br />Project Type:<br />CISTERN INFO<br />Size:<br />Water Source:<br />Use:<br />Private<br />Non-Potable toilets<br />3x 850 gallons<br />Rainwater<br />Toilets/Irrigation<br /><br />
  12. 12. Luxury “Off-the-Grid – All water usage; Tampa, FL<br />Project Owner:<br />Project Type:<br />CISTERN INFO<br />Size:<br />Water Source:<br />Use:<br />Private<br />Whole House Potable + Greywater<br />4x 1250 gallons<br />Rainwater<br />All applications + greywater tank for toilets<br />RAINWATER SERVICES MOST INNOVATIVE - HYBRID<br /><br />
  13. 13. What is rainwater harvesting?<br />Collecting rainwater<br />Storing rainwater<br />Using rainwater<br />Stormwater management<br /><br />
  14. 14. Rainwater Characteristics<br />The natural water cycle is very efficient in screening out contaminants that are normally found in ground water and other sources. <br />Rainwater does not come in contact with the soil, and so it does not contain:<br />harmful bacteria<br />dissolved salts<br />minerals<br />heavy metals<br /><br />
  15. 15. Possible Uses for Rainwater<br />Irrigation<br />Other Outdoor<br />Vehicle washing<br />Fountains<br />Swimming pool makeup<br />Industrial<br />Industrial processes instead of municipally treated water <br />Cooling tower makeup<br />Indoor<br />Toilet flushing<br />Potable<br />Drinking<br />Laundry<br /><br />DISCUSSION SEED:<br />Ease watering restrictions when RHS used for the above??<br />
  16. 16. Water Use Focus<br />Indoor Outdoor<br />Note: Different design criteria, regulations, costs, and health concerns will apply for systems other than those intended strictly for landscape irrigation.<br /><br />
  17. 17. What are important uses to offset? <br />Q:<br />A:<br />Irrigation.<br />In some parts of Florida, irrigation can account for over 50% of a single family’s water use!<br />Percentage can rise higher during dry early summer months!<br /><br />
  18. 18. Water Use Focus- SF Outdoor<br />Maximum Average Month- May<br />250 gallons/day/account (g/d/a)<br />140-170 g/d/a indoor<br />Approximately 100 g/d/a outdoor(40%)<br />Varies by Location/Age of home/irrigation system (south Hillsborough 305 g/d/a, St. Pete 158 g/d/a)<br />Irrigation use 1500-2500 gallons/irrigation<br /><br />
  19. 19. What are important uses to offset? <br />Q:<br />A:<br />Non-potable (e.g. toilets)<br />Up to 20 gallons per person per day or more<br />Other: car washing, pool filling, etc…<br /><br />
  20. 20. Water Use Focus- Indoor(w/out conserving fixtures)<br />Typical fixtures<br />Water-saving fixtures<br /><br />
  21. 21. Water Use Offset - SUMMARY<br /><br />Two biggest usages: <br />NON-POTABLE<br />Irrigation: Easiest to control/adjust<br />Toilets: Don’t stop using them, please, but…<br />Rainwater<br />Grey(ay)-water<br />OFFSET Non-potable uses to make a substantial water-savings contribution <br />
  22. 22. What are important uses to offset? <br />Q:<br />A:<br />Potable<br />Simplified plumbing<br />Health/safety is #1<br />Reliability<br /><br />
  23. 23. General Considerations:POTABLE APPLICATIONS<br />HEALTH<br />HEALTH<br />Treatment<br />Testing<br />RELIABILITY<br />Alternate source (if available?)<br />SERVICEABILITY<br />Accessibility<br />Replaceable/serviceable components<br />REGULATORY<br /><br />
  24. 24. What is another important application? <br />Q:<br />A:<br />Stormwater Management<br />Low Impact Development<br />Reduce non point source runoff<br />Groundwater recharge<br /><br />
  25. 25. anatomy of a Rainwater Harvesting System<br />
  26. 26. System Anatomy<br />Rain<br />The ON button!<br />Catchment Area<br />(roof)<br />Conveyance<br />(gutters/downspouts)<br />Pretreatment<br />(screen filters, first-flush)<br />Storage<br />(cistern)<br />Treatment & Distribution<br />Source: Harvesting Water for Landscape Use by Patricia H. Waterfall, p. 34 Original diagram was modified for this application.<br /><br />
  27. 27. Catchment<br />Roof acts as the catchment area<br />Size <br />Determines harvesting potential<br />Surface material<br />Determines quality<br />The slicker, the better<br />For potable, metal is preferred<br />Courtesy: ARCSA<br /><br />
  28. 28. Conveyance & Pretreatment<br />Water quality is determined by what is conveyed into the storage tank(s)<br />Roof surface debris<br />Twigs and leaves<br />Dust<br />Bird droppings<br />Other debris<br /><br />
  29. 29. Conveyance & Pre-treatment<br />Leaf Guards<br />First line of defense<br />Screened rain heads<br />Finer, pre-tank protection<br /><br /><br />
  30. 30. First Flush Devices<br />Downspout (wall-mounted) <br />Underground<br /><br /><br />
  31. 31. First Flush Devices<br />Prevents initial volume (“first-flush”) of roof runoff from entering storage tanks.<br />After a rainfall event, the “dirty” water is released through a slow-release valve, to reset for the next rainfall.<br />10-50 gallons per 1000 sf roof area<br />Optional for irrigation only if contaminant load is minimal<br /><br /><br />
  32. 32. Cistern Anatomy<br />Lid or manway<br />Secured tightly to avoid entrance by children and animals.<br />Vent<br />Use fine mesh screen to keep mosquitoes out<br />Overflow<br />Inlet<br />Max Water Level<br />Use flap valve or other methods to keep insects and animals out<br />From downspouts<br />Turbulence calming device (optional)<br />To prevent remixing of sediment<br />Storage<br />Floating Suction Filter<br />(cistern)<br />Outlet<br />Tank Pad<br />To distribution<br />Source: Rainwater Harvesting Planning and Installation Manual, January 2009, Figure 12.5. Original diagram was modified for this application.<br />Anaerobic / Sediment<br />Drain<br />pacia<br /><br />
  33. 33. Distribution<br />Select appropriate pump/pressure tank for water demand<br />Connect to disinfected indoor supply and/or irrigation system<br />Makeup water supply (if available) for low-water and/or poor water quality conditions<br />Backflow prevention!!!<br />Backflow prevention!!!<br /><br />
  34. 34. Major Distribution Components:RELIABILITY<br /><ul><li>Pump
  35. 35. Make-up valve
  36. 36. Backflow prevention</li></ul><br />
  37. 37. Distribution:EXAMPLE<br /><br />
  38. 38. Treatment<br />Water quality must meet appropriate standards for intended application<br />Example: Indoor potable = NSF 53 (cysts) + NSF 55A (UV) = VERY COMPLEX<br />Example: Indoor non-potable (toilets) = greywater dye injection = VERY COMPLEX<br />IRRIGATION= MINIMAL TREATMENT<br />Particulate/sediment removal<br />Similar to well-water supplies<br />Subject to local regulations<br /><br />
  39. 39. Treatment: POTABLE<br />Treatment processes<br />Sediment/filtration<br />2 or more stage + carbon<br />NSF 53 = cyst removal<br />Disinfection<br />NSF 55A = UV treatment of surface water<br />Other disinfection options:<br />Chlorine, Ozone, RO, etc…<br />All Rainwater Services potable systems meet NSF 53 and 55A <br /><br />
  40. 40. Treatment: POTABLE<br /><br />
  41. 41. Disinfection & Treatment:EXAMPLE<br /><br />
  42. 42. Disinfection & Treatment:EXAMPLE<br /><br />
  43. 43. DOLLARS & CENTS<br />
  44. 44. Initial Investment Issues<br />Rule of Thumb<br />Cistern to Installation Cost Ratio<br />60:40<br />WERF User’s Guide to the BMP and LID Whole Life Cost Models, 2009<br /><br />
  45. 45. Initial Investment Issues<br /><br />
  46. 46. Cost for Cistern<br />Based on Table 6.1 of the Texas Manual on Rainwater Harvesting, 2005<br /><br />
  47. 47. Estimated Costs for System<br />The Texas Manual on Rainwater Harvesting, 3rd Edition, Table 6.1 and WERF User’s Guide to the BMP and LID Whole Life Cost Models, 2009<br /><br />
  48. 48. Maintenance Responsibilities<br />Check for debris in tank<br />Tank should be cleaned out about once a year<br />Inspect gutters and downspouts regularly<br />Remove debris<br />First flush bypass<br />Check drain holes are clear for proper function<br />Inspect downspout seals and entrances<br />Check for leaks<br />Similar maintenance to well systems<br /><br />
  49. 49. Sizing & Reliability<br />
  50. 50. Sizing and Reliability Objectives<br />How to calculate rainfall capture potential<br />Determining water use demand<br />Passive irrigation<br />How to insure the right water quality in your tank<br />Determining if the water supply is reliable<br />Resources for further investigation<br /><br />
  51. 51. System Sizing<br />Q:<br />A:<br />DEMAND!<br />What dictates size of storage?<br />Captured water potential?<br />Water demand?<br /><br />
  52. 52. System sizing<br />There are many methods for sizing a system<br />Method considered today:<br />Demand Method<br /><br />
  53. 53. Step 1:<br />Rainfall Capture Potential<br /><br />
  54. 54. How much can be collected?<br />Variables & Formula<br />Rainfall Capture Potential<br />NOTE:<br />A conversion factor is needed in order to convert inches and square feet into gallons!<br />(discussed in the next few slides)<br />A x R = G<br />A = Catchment Area of building (square feet)<br />R= Rainfall (inches)<br />G= Total volume of Collected Rainwater (Gallons)<br /><br />
  55. 55. Size of Catchment Area<br />Basic Area Calculations<br />Get catchment area by:<br />A*= length x width <br /> = catchment area<br />The Texas Manual on Rain Water Harvesting, 3rd Edition, page 29<br />*NOTE It is the “footprint” of the roof that matters.<br /><br />
  56. 56. Rainfall Data<br />Use rainfall data by month<br />R = inches of rainfall (by month)<br />Sources for rainfall data:<br /><br /><br /><br />
  57. 57. Amount of Rainfall<br />Use this:<br />Rule of Thumb<br />Approximately one inch of rain falling on one square foot of area = 0.623 gallons<br />1 square foot<br />1” inch<br />Converts inches of rain X square foot -> gallons<br /><br />
  58. 58. Remember this number:<br />0.623<br />This number is the conversion factor from:<br />It can also be used for calculating irrigation water use.<br />inch X square foot -> gallons<br /><br />
  59. 59. EXAMPLE<br />For a 2000 square foot roof:<br />G = A X R X0.623<br />= 2000 ft2x 2 in x 0.623<br />G= 2,492 gallons<br />rainfall<br />conversion factor<br />area<br /><br />
  60. 60. System Efficiency<br /><ul><li>100% of rain is NOT collected</li></ul>Assume about 80% is captured<br />So, use<br />evaporation<br />←<br />Rule of Thumb<br />0.5 gallons<br />(instead of 0.623 gallons)<br />←<br />spillage<br />←<br />first flush<br /><br />
  61. 61. EXAMPLE<br />Assuming 80% is captured, a 2000 square foot roof:<br />G = A X R X0.5<br />= 2000 ft2x 2 in x 0.5<br />G= 2,000 gallons<br />conversion factor<br />with 80% efficiency<br />area<br />rainfall<br /><br />
  62. 62. Step 2:<br />Water Use Demand<br /><br />
  63. 63. How much is used?<br />Variables & Formula<br />Irrigation Demand Calculations<br />A x ET x0.623= G<br />A = Area to be irrigated (SF)<br />ET= Evapotranspiration rate<br />0.623= conversion factor<br />G= Total amount of anticipated usage (Gallons)<br /><br />
  64. 64. Indoor Use Demand Calculations<br />gpcd x #persons= G<br />gpcd= gallons per person per day used indoors<br />G= total amount of anticipated usage (Gallons)<br /><br />
  65. 65. Water Source Reliability <br />To what degree is rainwater reliable as a main source of water supply?<br />Rainwater varies from year to year<br /><br /><br />
  66. 66. More than enough rain<br />Not enough rain<br /><br />
  67. 67. More than enough rain<br />Not enough rain<br /><br />
  68. 68. Deficit<br />Surplus<br />* Based on a 2,000 sq. ft. catchment area , 500 sq. ft. of turf, with adjusted rainfall quantities.<br /><br />
  69. 69. Sizing by Irrigation Need<br />Deficit = 600 gallons +/-<br /><br />
  70. 70. Advice on Size of Storage<br />Adjust anticipated irrigation use when choosing a smaller tank<br />Compromise on cistern size<br />Start small. You can always add a second cistern later.<br /><br />
  71. 71. Other Irrigation Use Related Options<br />Use Passive Irrigation<br />Minimize size of turf<br />Reduce to 1/3 of existing size<br />Rain Gardens<br />Drip Irrigation<br /><br />
  72. 72. red tape<br />
  73. 73. Regulatory Consideration<br />Engineering, engineering, engineering<br />Building codes<br />Graywater (for non-potable)<br />Plumbing<br />Electrical<br />Health Departments<br />Local<br />State<br />EPA: Guidelines for surface water treatment<br /><br />
  74. 74. Regulatory Considerations:ENGINEERING<br />Plumbing<br />Makeup water controls<br />Treatment<br />Backflow prevention<br />Civil<br />Stormwater drainage<br />Electrical<br />Makeup water controls<br />Distribution/treatment components<br />RHS is relatively new/misunderstood. Few guidelines/codes/laws exist. Those that do aren’t necessarily clear. To ensure all building codes and building department concerns are met, <br />MUST HAVE QUALITY ENGINEERING!<br /><br />
  75. 75. Regulatory Considerations:BUILDING CODES<br />Classification of rainwater leads to confusion<br />IPC does not directly address rainwater, which leads to confusion and misunderstanding<br />Too often, rainwater is considered as “graywater” for lack of a better definition<br />Graywater = “waste discharged from lavatories, bathtubs, showers, clothes washers, and laundry trays.” (IPC 2006; Appendix C: C101.9)<br />Rainwater is not graywater!!<br />Rainwater IS surface water<br />Surface water is suitable water supply (Florida Building Code 2007: Plumbing Code; Section 202)<br />Stormwater drainage<br />Too often overlooked/afterthought<br />Vertical and horizontal leaders must be sized appropriately (FBC 2007: Plumbing Code; Section 1106)<br />Tampa Bay 100 year rainfall event = 5” <br />What flows into tanks must flow out at same rate<br />All downspouts lead to a common point. Total flow rate is cumulative.<br />When in doubt, scale up the overflow<br /><br />
  76. 76. Regulatory Considerations:HEALTH DEPARTMENTS<br />Classification:<br />Surface water private water supplies<br />For private water supplies, no state code requiring water quality sampling exists<br />However, recommended to test with same frequency as public well and/or surface water systems<br />Rainwater Services tests new potable systems for bacteria, lead and nitrates upon installation and as needed thereafter <br /><br />
  77. 77. Regulatory Consideration:EPA<br />Defines surface water<br />Rainwater harvested in cisterns falls under the surface water definition<br /> Manual for Individual and Non-community Water Supply Systems<br /> United States EPA, Office of Water<br />Provides standards for drinking water contaminants<br /><br /><br />
  78. 78. Summary<br />Harvested rainwater is a viable and practical water supply to offset a number of uses<br />For potable applications, strict attention must be paid to health, reliability & regulatory concerns<br />An effective system begins with proper design<br />Finished product must meet recognized standards for intended application<br />Fail-safe reliability (redundancy) should be considered<br />Design and construction is a collaborative effort involving various trades, engineers and building officials<br />Education is key to widespread adoption of rainwater harvesting codes, regulation and guidelines<br /><br />
  79. 79. Many thanks…<br /><br />
  80. 80. Trade Talk Discount<br /><br />HELP IMPROVE OUR WEBSITE!<br />Visit<br />Search: “Fatboy”<br />Add to cart<br />Discount Code: BROOKER-CREEK<br />I’LL HELP INSTALL!<br />10% off everything else, unlimited!!<br /><ul><li>Tank only, excludes pump, fittings, labor, etc
  81. 81. Excludes tax + S/H</li></li></ul><li>Questions?<br />Brian Gregson<br /><br />@RainwaterServices<br />@RWServices<br /><br /><br />