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Whole House Rainwater Harvesting: Capturing and Using Rainwater for Potable Applications

For a number of reasons, rainwater harvesting is preferred not just for landscape irrigation but for whole house potable uses as well. Here we present advanced design concerns and strategies including reliability, safety, regulatory and legal issues.

Presented to the Conservation Coordination Consortium hosted at Tampa Bay Water, October 13, 2010

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Whole House Rainwater Harvesting: Capturing and Using Rainwater for Potable Applications

  1. 1. Whole House Rainwater Harvesting:<br />Capturing and Using Rainwater for Potable Applications<br />Brian Gregson<br />Rainwater Catchment Systems Accredited Professional<br />Photo credit:<br />REAL Building Group LLC<br /><br />Conservation Coordination Consortium<br />Tampa Bay Water <br />October 13, 2010<br />
  2. 2. Who we are<br />Irrigation Contractor<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 />Institutional rainwater toilet flushing in St. Pete<br />Potable RHS in St. Pete<br />Potable RHS in Tampa<br />Permitted greywater(??) in Tampa<br />Shifting focus to commercial applications<br /><br />
  3. 3. 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 />
  4. 4. The PROBLEM:<br />Population growth = greater demand on resources (power, water, etc)<br />Reduced reliance on 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 />
  5. 5. Rainwater Harvesting:A Sustainable Option<br /><br />Source:<br />
  6. 6. 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 />
  7. 7. 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 />
  8. 8. 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 />
  9. 9. 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 /><br />Courtesy: ARCSA<br />
  10. 10. 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 />
  11. 11. Conveyance & Pre-treatment<br />Leaf Guards<br />First line of defense<br />Screened rain heads<br />Finer, pre-tank protection<br /><br /><br /><br />
  12. 12. 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 /><br /><br />
  13. 13. First Flush Devices<br />Downspout (wall-mounted) <br />Underground<br /><br /><br />
  14. 14. 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 />Hose Bibb<br />pacia<br /><br />
  15. 15. 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 />
  16. 16. Major Distribution Components:RELIABILITY<br /><br /><ul><li>Pump
  17. 17. Make-up valve
  18. 18. Backflow prevention</li></li></ul><li>Distribution:EXAMPLE<br /><br />
  19. 19. Treatment<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 />
  20. 20. Treatment<br /><br />
  21. 21. Disinfection & Treatment:EXAMPLE<br /><br />
  22. 22. Disinfection & Treatment:EXAMPLE<br /><br />
  23. 23. 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 />
  24. 24. 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 />
  25. 25. 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 />
  26. 26. 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 />
  27. 27. 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 />
  28. 28. Summary<br />Harvested rainwater is a viable and practical water supply<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 potability<br />Fail-safe reliability (redundancy) must 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 />
  29. 29. Many thanks…<br /><br />
  30. 30. Questions?<br />Brian Gregson<br /><br />@RainwaterServices<br />@RWServices<br /><br /><br />