Rainwater 201: The Next Level of Rainwater Harvesting
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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. RAINWATER 201: The Next Level of Rainwater Harvesting Brian Gregson Rainwater Catchment Systems Accredited Professional Tri-County Extension Services Brooker Creek Preserve February 2nd, 2011
- 2. Outline INTRODUCTION OVERVIEW Why harvest rainwater? Applications DESIGN CONSIDERATIONS ANATOMY 101 Potable vs. non-potable Reliability COST REGULATORY CONSIDERATIONS www.rainwaterservices.com
- 3. Who we are Irrigation Contractor: PCCLB 10280 Specializing in highly efficient water-conservation solutions Drip/micro irrigation, landscape drainage RAINWATER HARVESTING FIRSTS: ARCSA AP in State of FL Permitted RHS in St. Pete Potable RHS in St. Pete Potable RHS in Tampa Permitted greywater(??) in Tampa www.rainwaterservices.com
- 4. Why harvest rainwater? Preserve potable water for drinking and indoor uses Stormwater management L.I.D. Contribute to responsible growth Larger volume = $$$$ www.rainwaterservices.com
- 5. The PROBLEM: Population growth = greater demand on resources (power, water, etc) Reduced reliance on “traditional” groundwater/surface water Sinkholes?? Pollution?? Greater reliance on “innovative” water supplies (e.g. desalination) RHS reduces demand on blended resources www.rainwaterservices.com
- 6. Rainwater Harvesting:A Sustainable Option www.rainwaterservices.com Source: www.stuckincustoms.com
- 7. Residential Home, St. Petersburg, FL CISTERN INFO Size: Water Source: Use: 1,000 gallons Rainwater Irrigation www.rainwaterservices.com FIRST SYSTEM PERMITTED AND APPROVED IN ST. PETE!
- 9. LEED Elementary School Remodel, St. Petersburg, FL www.rainwaterservices.com Project Owner: Project Type: CISTERN INFO Size: Water Source: Use: Jordan Park Elementary Institutional 2x 2,500 gallons Rainwater Toilet Flushing RAINWATER SERVICES FIRST BELOW-GROUND
- 10. Residential – Potable (Laundry) St. Petersburg, FL Project Owner: Project Type: CISTERN INFO Size: Water Source: Use: Private Potable indoor use 2x 550 gallons Rainwater Toilets/Laundry ST. PETE’S FIRST POTABLE SYSTEM www.rainwaterservices.com
- 11. Luxury Waterfront – Toilets/Irrigation; St. Petersburg,FL Project Owner: Project Type: CISTERN INFO Size: Water Source: Use: Private Non-Potable toilets 3x 850 gallons Rainwater Toilets/Irrigation www.rainwaterservices.com
- 12. Luxury “Off-the-Grid – All water usage; Tampa, FL Project Owner: Project Type: CISTERN INFO Size: Water Source: Use: Private Whole House Potable + Greywater 4x 1250 gallons Rainwater All applications + greywater tank for toilets RAINWATER SERVICES MOST INNOVATIVE - HYBRID www.rainwaterservices.com
- 13. What is rainwater harvesting? Collecting rainwater Storing rainwater Using rainwater Stormwater management www.rainwaterservices.com
- 14. Rainwater Characteristics The natural water cycle is very efficient in screening out contaminants that are normally found in ground water and other sources. Rainwater does not come in contact with the soil, and so it does not contain: harmful bacteria dissolved salts minerals heavy metals www.rainwaterservices.com
- 15. Possible Uses for Rainwater Irrigation Other Outdoor Vehicle washing Fountains Swimming pool makeup Industrial Industrial processes instead of municipally treated water Cooling tower makeup Indoor Toilet flushing Potable Drinking Laundry www.rainwaterservices.com DISCUSSION SEED: Ease watering restrictions when RHS used for the above??
- 16. Water Use Focus Indoor Outdoor Note: Different design criteria, regulations, costs, and health concerns will apply for systems other than those intended strictly for landscape irrigation. www.rainwaterservices.com
- 17. What are important uses to offset? Q: A: Irrigation. In some parts of Florida, irrigation can account for over 50% of a single family’s water use! Percentage can rise higher during dry early summer months! www.rainwaterservices.com
- 18. Water Use Focus- SF Outdoor Maximum Average Month- May 250 gallons/day/account (g/d/a) 140-170 g/d/a indoor Approximately 100 g/d/a outdoor(40%) Varies by Location/Age of home/irrigation system (south Hillsborough 305 g/d/a, St. Pete 158 g/d/a) Irrigation use 1500-2500 gallons/irrigation www.rainwaterservices.com
- 19. What are important uses to offset? Q: A: Non-potable (e.g. toilets) Up to 20 gallons per person per day or more Other: car washing, pool filling, etc… www.rainwaterservices.com
- 20. Water Use Focus- Indoor(w/out conserving fixtures) Typical fixtures Water-saving fixtures www.rainwaterservices.com
- 21. Water Use Offset - SUMMARY www.rainwaterservices.com Two biggest usages: NON-POTABLE Irrigation: Easiest to control/adjust Toilets: Don’t stop using them, please, but… Rainwater Grey(ay)-water OFFSET Non-potable uses to make a substantial water-savings contribution
- 22. What are important uses to offset? Q: A: Potable Simplified plumbing Health/safety is #1 Reliability www.rainwaterservices.com
- 23. General Considerations:POTABLE APPLICATIONS HEALTH HEALTH Treatment Testing RELIABILITY Alternate source (if available?) SERVICEABILITY Accessibility Replaceable/serviceable components REGULATORY www.rainwaterservices.com
- 24. What is another important application? Q: A: Stormwater Management Low Impact Development Reduce non point source runoff Groundwater recharge www.rainwaterservices.com
- 25. anatomy of a Rainwater Harvesting System
- 26. System Anatomy Rain The ON button! Catchment Area (roof) Conveyance (gutters/downspouts) Pretreatment (screen filters, first-flush) Storage (cistern) Treatment & Distribution Source: Harvesting Water for Landscape Use by Patricia H. Waterfall, p. 34 Original diagram was modified for this application. www.rainwaterservices.com
- 27. Catchment Roof acts as the catchment area Size Determines harvesting potential Surface material Determines quality The slicker, the better For potable, metal is preferred Courtesy: ARCSA www.rainwaterservices.com
- 28. Conveyance & Pretreatment Water quality is determined by what is conveyed into the storage tank(s) Roof surface debris Twigs and leaves Dust Bird droppings Other debris www.rainwaterservices.com
- 29. Conveyance & Pre-treatment Leaf Guards First line of defense Screened rain heads Finer, pre-tank protection http://9p-enterprises.com/LSpics.aspx www.rainwaterservices.com
- 30. First Flush Devices Downspout (wall-mounted) Underground http://www.rainharvesting.com/ www.rainwaterservices.com
- 31. First Flush Devices Prevents initial volume (“first-flush”) of roof runoff from entering storage tanks. After a rainfall event, the “dirty” water is released through a slow-release valve, to reset for the next rainfall. 10-50 gallons per 1000 sf roof area Optional for irrigation only if contaminant load is minimal http://www.rainharvesting.com/ www.rainwaterservices.com
- 32. Cistern Anatomy Lid or manway Secured tightly to avoid entrance by children and animals. Vent Use fine mesh screen to keep mosquitoes out Overflow Inlet Max Water Level Use flap valve or other methods to keep insects and animals out From downspouts Turbulence calming device (optional) To prevent remixing of sediment Storage Floating Suction Filter (cistern) Outlet Tank Pad To distribution Source: Rainwater Harvesting Planning and Installation Manual, January 2009, Figure 12.5. Original diagram was modified for this application. Anaerobic / Sediment Drain pacia www.rainwaterservices.com
- 33. Distribution Select appropriate pump/pressure tank for water demand Connect to disinfected indoor supply and/or irrigation system Makeup water supply (if available) for low-water and/or poor water quality conditions Backflow prevention!!! Backflow prevention!!! www.rainwaterservices.com
- 35. Make-up valve
- 38. Treatment Water quality must meet appropriate standards for intended application Example: Indoor potable = NSF 53 (cysts) + NSF 55A (UV) = VERY COMPLEX Example: Indoor non-potable (toilets) = greywater dye injection = VERY COMPLEX IRRIGATION= MINIMAL TREATMENT Particulate/sediment removal Similar to well-water supplies Subject to local regulations www.rainwaterservices.com
- 39. Treatment: POTABLE Treatment processes Sediment/filtration 2 or more stage + carbon NSF 53 = cyst removal Disinfection NSF 55A = UV treatment of surface water Other disinfection options: Chlorine, Ozone, RO, etc… All Rainwater Services potable systems meet NSF 53 and 55A www.rainwaterservices.com
- 41. Disinfection & Treatment:EXAMPLE www.rainwaterservices.com
- 42. Disinfection & Treatment:EXAMPLE www.rainwaterservices.com
- 43. DOLLARS & CENTS
- 44. Initial Investment Issues Rule of Thumb Cistern to Installation Cost Ratio 60:40 WERF User’s Guide to the BMP and LID Whole Life Cost Models, 2009 www.rainwaterservices.com
- 45. Initial Investment Issues www.rainwaterservices.com
- 46. Cost for Cistern Based on Table 6.1 of the Texas Manual on Rainwater Harvesting, 2005 www.rainwaterservices.com
- 47. Estimated Costs for System 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 www.rainwaterservices.com
- 48. Maintenance Responsibilities Check for debris in tank Tank should be cleaned out about once a year Inspect gutters and downspouts regularly Remove debris First flush bypass Check drain holes are clear for proper function Inspect downspout seals and entrances Check for leaks Similar maintenance to well systems www.rainwaterservices.com
- 50. Sizing and Reliability Objectives How to calculate rainfall capture potential Determining water use demand Passive irrigation How to insure the right water quality in your tank Determining if the water supply is reliable Resources for further investigation www.rainwaterservices.com
- 51. System Sizing Q: A: DEMAND! What dictates size of storage? Captured water potential? Water demand? www.rainwaterservices.com
- 52. System sizing There are many methods for sizing a system Method considered today: Demand Method www.rainwaterservices.com
- 53. Step 1: Rainfall Capture Potential www.rainwaterservices.com
- 54. How much can be collected? Variables & Formula Rainfall Capture Potential NOTE: A conversion factor is needed in order to convert inches and square feet into gallons! (discussed in the next few slides) A x R = G A = Catchment Area of building (square feet) R= Rainfall (inches) G= Total volume of Collected Rainwater (Gallons) www.rainwaterservices.com
- 55. Size of Catchment Area Basic Area Calculations Get catchment area by: A*= length x width = catchment area The Texas Manual on Rain Water Harvesting, 3rd Edition, page 29 *NOTE It is the “footprint” of the roof that matters. www.rainwaterservices.com
- 56. Rainfall Data Use rainfall data by month R = inches of rainfall (by month) Sources for rainfall data: http://www.ncdc.noaa.gov/oa/climate/online/ccd/nrmlprcp.html http://www.swfwmd.state.fl.us/data/wmdbweb/rainfall_data_summaries.php www.rainwaterservices.com
- 57. Amount of Rainfall Use this: Rule of Thumb Approximately one inch of rain falling on one square foot of area = 0.623 gallons 1 square foot 1” inch Converts inches of rain X square foot -> gallons www.rainwaterservices.com
- 58. Remember this number: 0.623 This number is the conversion factor from: It can also be used for calculating irrigation water use. inch X square foot -> gallons www.rainwaterservices.com
- 59. EXAMPLE For a 2000 square foot roof: G = A X R X0.623 = 2000 ft2x 2 in x 0.623 G= 2,492 gallons rainfall conversion factor area www.rainwaterservices.com
- 61. EXAMPLE Assuming 80% is captured, a 2000 square foot roof: G = A X R X0.5 = 2000 ft2x 2 in x 0.5 G= 2,000 gallons conversion factor with 80% efficiency area rainfall www.rainwaterservices.com
- 62. Step 2: Water Use Demand www.rainwaterservices.com
- 63. How much is used? Variables & Formula Irrigation Demand Calculations A x ET x0.623= G A = Area to be irrigated (SF) ET= Evapotranspiration rate 0.623= conversion factor G= Total amount of anticipated usage (Gallons) www.rainwaterservices.com
- 64. Indoor Use Demand Calculations gpcd x #persons= G gpcd= gallons per person per day used indoors G= total amount of anticipated usage (Gallons) www.rainwaterservices.com
- 65. Water Source Reliability To what degree is rainwater reliable as a main source of water supply? Rainwater varies from year to year http://www.swfwmd.state.fl.us/data/wmdbweb/rainfall_data_summaries.php www.rainwaterservices.com
- 66. More than enough rain Not enough rain www.rainwaterservices.com
- 67. More than enough rain Not enough rain www.rainwaterservices.com
- 68. Deficit Surplus * Based on a 2,000 sq. ft. catchment area , 500 sq. ft. of turf, with adjusted rainfall quantities. www.rainwaterservices.com
- 69. Sizing by Irrigation Need Deficit = 600 gallons +/- www.rainwaterservices.com
- 70. Advice on Size of Storage Adjust anticipated irrigation use when choosing a smaller tank Compromise on cistern size Start small. You can always add a second cistern later. www.rainwaterservices.com
- 71. Other Irrigation Use Related Options Use Passive Irrigation Minimize size of turf Reduce to 1/3 of existing size Rain Gardens Drip Irrigation www.rainwaterservices.com
- 72. red tape
- 73. Regulatory Consideration Engineering, engineering, engineering Building codes Graywater (for non-potable) Plumbing Electrical Health Departments Local State EPA: Guidelines for surface water treatment www.rainwaterservices.com
- 74. Regulatory Considerations:ENGINEERING Plumbing Makeup water controls Treatment Backflow prevention Civil Stormwater drainage Electrical Makeup water controls Distribution/treatment components 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, MUST HAVE QUALITY ENGINEERING! www.rainwaterservices.com
- 75. Regulatory Considerations:BUILDING CODES Classification of rainwater leads to confusion IPC does not directly address rainwater, which leads to confusion and misunderstanding Too often, rainwater is considered as “graywater” for lack of a better definition Graywater = “waste discharged from lavatories, bathtubs, showers, clothes washers, and laundry trays.” (IPC 2006; Appendix C: C101.9) Rainwater is not graywater!! Rainwater IS surface water Surface water is suitable water supply (Florida Building Code 2007: Plumbing Code; Section 202) Stormwater drainage Too often overlooked/afterthought Vertical and horizontal leaders must be sized appropriately (FBC 2007: Plumbing Code; Section 1106) Tampa Bay 100 year rainfall event = 5” What flows into tanks must flow out at same rate All downspouts lead to a common point. Total flow rate is cumulative. When in doubt, scale up the overflow www.rainwaterservices.com
- 76. Regulatory Considerations:HEALTH DEPARTMENTS Classification: Surface water private water supplies For private water supplies, no state code requiring water quality sampling exists However, recommended to test with same frequency as public well and/or surface water systems Rainwater Services tests new potable systems for bacteria, lead and nitrates upon installation and as needed thereafter www.rainwaterservices.com
- 77. Regulatory Consideration:EPA Defines surface water Rainwater harvested in cisterns falls under the surface water definition Manual for Individual and Non-community Water Supply Systems United States EPA, Office of Water Provides standards for drinking water contaminants http://www.epa.gov/safewater/standards.html www.rainwaterservices.com
- 78. Summary Harvested rainwater is a viable and practical water supply to offset a number of uses For potable applications, strict attention must be paid to health, reliability & regulatory concerns An effective system begins with proper design Finished product must meet recognized standards for intended application Fail-safe reliability (redundancy) should be considered Design and construction is a collaborative effort involving various trades, engineers and building officials Education is key to widespread adoption of rainwater harvesting codes, regulation and guidelines www.rainwaterservices.com
Notas del editor
- I love getting in front of audiences and talking about water conservation because I’m passionate about it. Heck, I founded a company focused on water conservation. So anything involving saving water is important to me…
- RHS= Rainwater Harvesting SystemFirst, listed.Future: More commercial, more potable and/or toilet flushing (bring plumber on board)
- TBW, SWFWMD, local govs, other players invest a lot of effort (time/$$) into domestic water infrastructureImportant to ensure those resources last as long as possible, minimize continued investmentA good strategy would be to, not only conserve water, but also to use an alternative water source (rainwater) for irrigation, and save our precious potable drinking water for drinking and other indoor uses.LID = Low Impact DevelopmentSite retention = reduced demand on stormwater processingNot as cost-effective for small volumes, but for large = huge potential financial savings
- Simple supply and demandRapidly and continuously growing region = resource demandsIncreased demand on traditional water supplies (ground/surface water) = growing reliance on “innovative” supplies (desal)Production/delivery of water has a large carbon footprintGroundwater demand leads to unstable geology (sinkholes)??Increased pollution = increased treatment efforts (surface waters)As demand on “innovative” supplies increase, cost of blended product increasesRHS is an alternative supply that reduces demand on produced water resources
- How do we prolong development of new water supplies?As a part of effective conservation: RAINWATER HARVESTINGPoint source usage = minimal infrastructureSegue to examples
- First LEED Gold in FloridaEPA Water Star??Reportedly approx. 1 month irrigation without supplementalFlorida-friendly landscaping
- Cistern 1: IrrigationCistern 2: toilets??Overflow discharge to drainage field planted with banana plants (removes nutrients before percolating into groundwater)
- Reclaimed backup supply (valve switched, not direct tank fill)1 tank = toilets2 tanks = irrigation
- Low-profile, under house: great use of otherwise underutilized space
- Rainwater harvesting is the collecting and storing of rainwater. Collection is usually from a roof, and storage is in a catchment tank. Using = pumping, distribution, etc. Stormwatermanagement relates to reduction of runoff, groundwater recharging, etc (overflow discharge)
- Rainwater is very clean.
- There are many uses for rainwater. Irrigation would be the application requiring the least amount of treatment before use.All contribute to offsetting municipal supplies.
- OUTDOOR (esp. irrigation) = flexible: we have the most controlINDOOR = static or fixed demand
- Since irrigation consumes most of our potable water use, let’s start here.Perfectly good drinking water, poured on lawn.In order to reduce usage of potable infrastructure, irrigation is easiest usage to control********************************************************************Irrigation remained the largest use of freshwater in the United States and totaled 137 Billion gallons/day for 2000. Since 1950, irrigation has accounted for about 65 percent of total water withdrawals, excluding those for thermoelectric power.The above info came from http://pubs.usgs.gov/circ/2004/circ1268/index.html
- FLEXIBLE DEMAND: User has most control over conservation activitiesOFFSETING IRRIGATION USE HAS THE SINGLE BIGGEST IMPACT VIS-A-VIS HOMEOWNER WATER CONSERVATION
- Biggest usage that doesn’t require potableIndoor, toilets make the most senseUp to 20 gallons: inefficient fixturesApprox. 10 gallons: water-saving fixtures
- Example of indoor demand: toilets=largest
- Irrigation #1, toilets #2 users of potable water: ridiculousEasy to alter irrigation usageNot easy to limit toilet usage but can be offset with low-flow fixture and alternative water supply
- Sameplumbing as any other typical building (no need for separate pipework)Water quality is paramount! Proper disinfection, etcReliability: power failures, drought, etc.
- HEALTH is #1 priority. (repeated for emphasis).Treatment to potable standardsTesting to ensure standards are metReliable (don’t want loss of water during shower)Ease of serviceRegulatory = building, health, etcProbably incomplete list
- Typically, water from roofs runs down impermeable surfaces, collecting pollutants, discharges into storm drainage system, which ultimately leads to the bay.Similar to domestic supply infrastructure, large investment in stormwater infrastructure, therefore, maximize lifetime by minimizing inflowReduce runoff = reduce demand on stormwater treatment infrastructureReduce runoff = reduce direct discharge of pollutantsGroundwater infiltration/recharge = less demand on “alternative” water suppliesThink of potable and stormwater infrastructure as one combined unit; using LID principles, complement and enhance each other
- Discussed possible offsets. Now, seque into system “anatomy”
- As it pertains to water qualityBig or small, residential or commercial, the harvesting system will have these components.Exact specifications determined by application.Irrigation only: SIMPLE (minimal filtration, well-water controls/pumps)Potable: COMPLEX (treatment, makeup controls, etc)
- The roof is what is used as the catchment area. (there are other surfaces, e.g. permeable driveways, swales, etc… but for simplicity, stick with roofs)Its size dictates how much rainwater can be captured. Material affects initial water quality.The slicker, the better
- Common senseGarbage in, garbage out
- First line of defense.Not reliable. When designing RHS, assume no leaf guards.Keeping limbs and leaves away from catchment area and from clogging conveyance is important in keeping cistern water quality pure.These products reduce maintenance needs while preventing debris from entering the cistern.
- First-flush or roof washerVolume to be diverted depends on contaminant loadMinimal (no large overhanging trees)= ~ 10 gallons/1000 sfHeavy (large overhanging tree canopy) = ~ 50+ gallons/1000 sf
- After passing through conveyance and pre-treatment, water enters tank(s)You will notice that cisterns have a lot pipes going in and out of them. This configuration can vary, but generally there will be an inlet, an outlet, an overflow and drain valve. A manway is also necessary for maintenance/cleaning. Never go inside alone or without a plan on how to get out.Inlet, outlet and overflow are self explanatory. Overflow:Engineering drainage design may need to come into play here. Common sense dictates for overflow to be directed away from tank/buildings where volume of water won’t cause erosion, flooding, carry organic material (especially if animals are present) into wells or water sources, cause standing water for long periods (mosquito breeding), etc. Over flow can be directed towards in place drainage system or can also be allowed to percolate into the ground via french drain, etc. Passive use of the overflow rainwater is desirable.Overflow outlets can be configured in different ways. If the overflow outlet draws from the bottom, it should be vented to prevent siphoning. Overflow outlets and vents should be equipped with a fine mesh screen to prevent mosquito entry.Anaerobic/Sediment zone is located in the bottom 6” or so of the tank. Here is where the ‘dirtier’ water and sediment tends to collect. Avoid drawing water from this portion of the tank.A hose bibb or drain valve is needed in order to drain the tank if needed. Bibb should be elevated 6” or so. Solids tend to accumulate at the bottom so elevating will help avoid clogging.The floating suction filter will allow water to be extracted in the cleaner area of the tank. Particles either settle at the bottom of the tank or float on top. Thus, the filter on the end of the hose will filter the remainder of the particles before sending the water to the irrigation system.Important to make sure all openings are sealed properly to avoid (1) mosquito infestation (2) animal intrusion and (3) children from entering the cistern.Tank should be placed on a level, stable foundation. This may consist of gravel or concrete pad. FACT: Water weighs 8.34 pounds per gallon. A 1000 gallon cistern can weigh up to 8340 gallons when full. Imagine what would happen if an unstable tank tips over.
- Water must get withdrawn from tanks to be useful
- Pump:Make-up: valve to switch to other water source when tanks run dry or water quality is low-In this case, normally open = fail-safe redundancy
- Dual pump for increased demandNo less than 3 backflow preventers in this roomSwitching controls for make-up waterUSE EXISTING SPRINKLER PUMP??
- NOTE 1: Dye injection for toilet flushing, per greywater plumbing codes. If treated for potable, must meet EPA standards, approval from health, water resources departmentsNOTE 2: Backflow to prevent public water supply (if cross-connected to municipal water)UV preferred for small-scale RHS because non-chemical (e.g. chlorine) and doesn’t waste water (e.g. RO)NSF 53: Guideline for removal of cysts: 0.5 um carbon.NSF 55A: Guideline for ultraviolet treatment of previously untreated surface waters. Must be pre-treated to NSF 53.All RWS potable systems use components that meet NSF 53 and 55A (also 61: components safe for drinking water)
- NOTE 1: Dye injection for toilet flushing, per greywater plumbing codes. If treated for potable, must meet EPA standards, approval from health, water resources departmentsNOTE 2: Backflow to prevent public water supply (if cross-connected to municipal water)UV preferred for small-scale RHS because non-chemical (e.g. chlorine) and doesn’t waste water (e.g. RO)NSF 53: Guideline for removal of cysts: 0.5 um carbon.NSF 55A: Guideline for ultraviolet treatment of previously untreated surface waters. Must be pre-treated to NSF 53.All RWS potable systems use components that meet NSF 53 and 55A (also 61: components safe for drinking water)
- Typical potable treatment: 2 (or more) stage sediment/carbon + UV disinfection
- Pump2-stage sediment/carbonUVNote: backflow prevention
- Pump3-stage sediment/carbonUVNote: makeup controlsFloat switch and UVT switch wired in series to NO valve on mains water
- Discussed possible offsets. Now, seque into system “anatomy”
- So, What does all this cost?Cistern + equipment: generally 60% of the total cost of system; 40% is the installation.Per gallon cost decreases as cost increases
- Per gallon cost decreases as volume increasesAnother rule of thumb: Since most applications have limited space and budget and given that most installers have never encountered a client whose cistern was too large, it is often recommended that one purchase the largest cistern that their space and budget will allow.
- Excludes labor!
- Cost per gallon decreases with increased volume. Not linear relationship!!!EXCLUDES FILTRATION, CONVEYANCE, FIRST-FLUSH
- Passive irrigation – what it is, how it conserves water, and how it can work for you!
- Demand Method - Based purely on anticipated water needs***************************************************************Water balance method – (1) Maintain a monthly balance, (2) Start with an assumed volume (3) Add volume captured (4) Subtract monthly demand (5) Evaluate size and affordability of storage capacity.Major storm method – This method is used in order to capture every drop available at a major storm event (or every available drop during wettest month). ProvidesPro- Minimum cistern volume needed to capture rainfall for this size stormCon- Not based on water usageWhat is the quick calculation method? A ‘quick and dirty’ way of calculating water quantities.
- How to calculate rainfall capture potentialThis means, how much rain can be collected on the roof that you have.
- To calculate how many gallons of water that can be collected, use this basic formula:Area of Roof (generally in square feet)Rainfall (inches)Then multiply to obtain amount in gallons.
- The area of catchment surface is only as big as the footprint of your house. Think of how a raindrop sees your roof as it makes its way down. Whether it is slanted or flat, it will fall within this area. That is the area we are concerned about. So, you can multiply the length and width of roof area, or use the square footage of building.******************************************************************************************************************************For more information see http://www.harvestingrainwater.com/rainwater-harvesting-inforesources/water-harvesting-calculations/
- One ‘chunk’ of rain….One inch deep x 1 square foot = 0.623 gallons of rainwater collected
- Ever bake a batch of cookies? Even though the recipe states that you can bake a dozen, it’s never exactly that much, right?Well, try as you may, you will probably not collect every drop of water from your roof. You will lose water due to evaporation from your hot roof, spillage or overrunning of your gutters, or other factors. So, to compensate, lower factor down to .5 gallons/square foot per inch of rain.******In case someone asks: Why remember .623 when you tell them to use 0.500 ? 0.623 is the CONVERSION FACTOR. 0.5 is not. 0.5 takes into account water losses in the system. 0.5 = 0.623 (conversion factor) * 0.8 (runoff coefficient)**************************************************************************************************************Runoff coefficient of 0.80 is a conservative number from Civil Engineering Reference Manual for the PE Exam, Eighth Edition, by Michael R. Lindeburg, PE, page A-43.
- In case someone asks: Why remember .623 when you are using 0.500 ? 0.623 is the CONVERSION FACTOR. 0.5 is not. 0.5 takes into account water losses in the system. 0.5 = 0.623 (conversion factor) * 0.8 (runoff coefficient)******************************************Instructions to Presenter: Arrow takes you to slide where conversion factor with water losses is broken down by units for those who require further explanation.
- This is where we calculate how much water is used in irrigation.
- The formula for calculating water demand, in this case: how much water will be used for irrigation, is very similar to our first formula for calculating water collection potential. We consider the area to be irrigated (in square feet), the conversion factor of 0.623. The only difference is that, instead of inches of rain, we use something called ET rate.
- The formula for calculating water demand, in this case: how much water will be used for irrigation, is very similar to our first formula for calculating water collection potential. We consider the area to be irrigated (in square feet), the conversion factor of 0.623. The only difference is that, instead of inches of rain, we use something called ET rate.
- To what degree is rainwater reliable as a main source of water supply?Rainwater varies from year to yearMay need alternative source- BUILD YOUR SYSTEM TO MEET YOUR LANDSCAPE NEEDS IN A FLORIDA DROUGHTAlternative Water sourcesAC CondensateShallow Wells
- This graph shows the amount of water (in inches) for irrigation for a St. Augustine lawn per month (shown in green) and the average rainfall for our area (the blue line). As can be seen, there are times during the year that there is more than sufficient rainfall for our lawns (white space between blue line and green shading), but other times there isn’t enough rain (shown where blue line dips into green shading).
- This graph shows the amount of water (in inches) for irrigation for a St. Augustine lawn per month (shown in green) and the average rainfall for our area (the blue line). As can be seen, there are times during the year that there is more than sufficient rainfall for our lawns (white space between blue line and green shading), but other times there isn’t enough rain (shown where blue line dips into green shading). During the last 3 years, we’ve been experiencing less than average rainfall. In order to show this, the average yearly rainfall has been adjusted by 50%. The dashed blue line shows this as the ‘adjusted’ yearly rainfall. This is just a conservative number (factor of safety of 2), assuming we only receive half of the average rainfall.
- What would happen is that we could actually capture the same number of inches of rain…and store it until we needed it?Suppose we had a 2000 sq. ft. catchment area and 500 sq. feet of St. Augustine turf to irrigate. This graph shows how many gallons of rainwater can be collected and how much is needed for irrigation. Now we can clearly see parts of the year where there is a surplus and others where there is a deficit – or need – of irrigation water. In this particular instance, a surplus occurs between June and late September. A small Deficit occurs in March through late May.The deficit that occurs in April and May, which accounts for about 600 gallons, should be added to total amount needed in April. The minimum capacity required during April is 1,915 gallons (1,308 + 407 + 200) to make it through the ‘dry period’ of April and May. This happens to be the maximum amount of volume stored throughout the year, as no other month requires this much volume. For this particular case, an adequately sized cistern is one whose capacity is approximately 2,000 gallons.
- What size cistern is needed?Here, green represents the harvested rainwater used for irrigation and the blue, the rainwater that is stored in the cistern.The deficit that occurs in April and May, which accounts for about 600 gallons, should be added to total amount needed in April. The minimum capacity required during April is 1,915 gallons (1,308 + 407 + 200) to make it through the ‘dry period’ of April and May. This happens to be the maximum amount of volume stored throughout the year, as no other month requires this much volume. For this particular case, an adequately sized cistern is one whose capacity is approximately 2,000 gallons.
- Adjust how much you intend to water. Maybe just water front yard and flower bed. Let the back go.Always add later, unless considering underground. Another animal.
- Conservation can be a big part of your overall plan in using rainwater for irrigation. One good method for irrigation can be passive irrigation. What is that? Should we build in FYN concepts here? Yes!
- Complex systems require collaboration and knowledge of various regulations, laws and guidelinesEngineer is your best friendMUST HAVE QUALITY ENGINEERINGIncludes meetings with building department officials as needed. Keep everyone in the loop.Commonly, rainwater is considered as “graywater” for lack of a better definition. However, according to IPC 2006 (Appendix C: C101.9), Gray Water is defined asGray Water: “waste discharged from lavatories, bathtubs, showers, clothes washers, and laundry trays.”IPC 2006; Appendix C: C101.9Since water collected in RHS is not supplied by any of the sources listed in this definition, an argument can reasonably be presented that rainwater is NOT graywater. As such, RHS should not be subject to the same code interpretations as graywater.Since surface waters (including stored rainwater) are suitable as private water supplies, the only limitations on their use for the proposed applications pertain to their potability.Potable Water: “Water free from impurities present in amounts sufficient to cause disease or harmful physiological effects and conforming to the bacteriological and chemical quality requirements of the Public Health Service Drinking Water Standards or the regulations of the public health authority having jurisdiction.”Florida Building Code 2007: Plumbing Code; Section 202Stormwater often the most overlooked part of RHSInexperienced designers don’t consider the cumulative flow rate (if 3 x 4” pipes going in, better have at least 6” pipe going out).Example: builder responsible for storm drainage. RWS left 6” pipe stubbed out from tanks for overflow of catchment off a 4000 sf roof. Builder connected with 3” pipe. Led to “geyser” and flood of neighbor’s low-lying pool. Pool damaged, popped out of ground, etc…Defines surface waterRainwater harvested in cisterns falls under the surface water definition Manual for Individual and Non-community Water Supply Systems United States EPA, Office of WaterProvides standards for drinking water contaminants
- Engineer is your best friendMUST HAVE QUALITY ENGINEERINGIncludes meetings with building department officials as needed. Keep everyone in the loop.
- Commonly, rainwater is considered as “graywater” for lack of a better definition. However, according to IPC 2006 (Appendix C: C101.9), Gray Water is defined asGray Water: “waste discharged from lavatories, bathtubs, showers, clothes washers, and laundry trays.”IPC 2006; Appendix C: C101.9Since water collected in RHS is not supplied by any of the sources listed in this definition, an argument can reasonably be presented that rainwater is NOT graywater. As such, RHS should not be subject to the same code interpretations as graywater.Since surface waters (including stored rainwater) are suitable as private water supplies, the only limitations on their use for the proposed applications pertain to their potability.Potable Water: “Water free from impurities present in amounts sufficient to cause disease or harmful physiological effects and conforming to the bacteriological and chemical quality requirements of the Public Health Service Drinking Water Standards or the regulations of the public health authority having jurisdiction.”Florida Building Code 2007: Plumbing Code; Section 202Stormwater often the most overlooked part of RHSInexperienced designers don’t consider the cumulative flow rate (if 3 x 4” pipes going in, better have at least 6” pipe going out).Example: builder responsible for storm drainage. RWS left 6” pipe stubbed out from tanks for overflow of catchment off a 4000 sf roof. Builder connected with 3” pipe. Led to “geyser” and flood of neighbor’s low-lying pool. Pool damaged, popped out of ground, etc…For private water supplies, no state code requiring water quality sampling existsHowever, recommended to test with same frequency as public well and/or surface water systemsRainwater Services tests new potable systems for bacteria, lead and nitrates upon installation and as needed thereafter
- “Surface Water: Surface water accumulates mainly as a result of direct runoff from precipitation. Precipitation that does not seep into the ground or evaporate, flows over the ground surface and is classified as direct runoff…In some areas, a source of water is the rainfall intercepted by roof surfaces on homes, barns, and other buildings. Water from those surfaces can be collected and stored in tanks called cisterns.”Manual for Individual and Non-community Water Supply SystemsUnited States EPA, Office of WaterDocument: EPA 570/9-91-004In order for regulatory agencies to evaluate potability of water supplies, the EPA provides updated standards for drinking water contaminants (see: http://www.epa.gov/safewater/standards.html). Treatment methods must meet or exceed the values specified by these standards.
- Also cost will become more relevant as existing resources are depletedBackflow, testing, make-up supply, communicationEngineer is best friendNSF 53, NSF 55A, etcMake-up water controls. Not only level switched, also water quality switched.All involved from the beginning. All on same page throughout process.Still a lot of questions and misunderstanding. Need more education of all involved: - property owners - builders - engineers/architects (designers) - building officials - etc
- Simple DIY tank. Discount for Fatboys. Please give feedback on how to improve websiteI’ll help: local area only (duh!)10% off, website or not, installation, service, etc… everything!
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