Water Harvesting for Landscape Irrigation
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The document discusses methods for harvesting rainwater and reusing greywater for landscape irrigation in order to conserve potable water supplies. It describes the components of a basic rainwater harvesting system and their benefits. It also outlines the process for estimating water supply and demand from rainfall. The document provides examples of different rainwater storage tank designs both above and below ground. It further discusses systems for recycling greywater from clothes washers and entire homes through subsurface drip irrigation and constructed wetlands.
Water Harvesting for Landscape Irrigation
- 1. Water Harvesting for Landscape Irrigation Rosalind Haselbeck & Rich Alianelli Building Green Futures Inc. CCSE April 19, 2012
- 2. Introduction: Who we are
- 4. Water Run-off: developed vs. natural Source: http://www.coastal.ca.gov/nps/watercyclefacts.pdf
- 5. Water Use, San Diego http://www.savewateroceanside.com/conservationtips.asp#graph
- 7. Components of Rainwater Harvesting for Irrigation Roof catchment area Gutters & downspout Storage Tank To drip system/hose Overflow Pump
- 8. Benefits of Rainwater Harvesting • Reduces personal water bills • Provides naturally soft, neutral pH water • Conserves water • Conserves energy • Erosion and flood control • Protects our beaches and rivers
- 9. Estimating Supply & Demand Source: Building Green Futures (www.buildinggreenfutures.com)
- 10. Above-ground Tanks Source: RainHarvest Systems Source: Tankworks Australia Source: BH Tanks Inc. Source: Bushman Tanks USA
- 11. Below-ground Tanks Source: Graf Rainwater Tanks Source: Rainwater Collection Solutions Source: Xerxes Fiberglass Tanks Source: Atlantis Water Management
- 13. A Rainwater Pillow Source: Building Green Futures (www.buildinggreenfutures.com)
- 14. Source: Building Green Futures (www.buildinggreenfutures.com)
- 15. 2) 8,500 gallon below-ground system with a geothermal loop field and barrels above ground
- 16. Underground Rainwater Storage: 8,000 gallons in Graf Carat Tanks
- 17. Corrugated steel tank with 10,000 gallon capacit
- 18. Using Earthworks
- 19. Greywater Recycling • Background • Clothes washer systems • Whole house systems • Constructed wetlands • Indoor non-potable
- 20. Why Use Greywater? • Reduce personal water bills • Conserve water & energy • Convert potential pollutants into nutrients • Reduce strain on treatment or septic systems • Enhance water quality and recharge groundwater • Conserve aquatic ecosystems • Grow plants!
- 21. Greywater Numbers • San Diego homes use 14 HCF water per month • 14 HCF = 10,472 gallons • Greywater ~ 50% indoor water use • By code, 40 gallons per day/occupant • 3 bdrm house 4,800 gallons greywater/month • Outdoor use > 50% total water
- 22. Defining Greywater • Greywater = Washwater • Excludes toilet wastes and kitchen scraps • Provides Phosphorus, Nitrogen, Potassium • Greywater systems are onsite wastewater treatment systems using subsurface irrigation
- 23. Why Use Greywater? • Reduce personal water bills • Create a sustainable landscape • Convert potential pollutants into nutrients • Conserve water & energy • Reduce strain on treatment or septic systems • Enhance water quality and recharge groundwater
- 24. Energy Down the Drain
- 25. Energy intensity = energy required to use a specific amount of water in a specific location water heaters pump stations pressurizing water (car wash Source: NRDC “Energy Down the Drain” 2004
- 26. Energy Savings with Low Flow Shower Head Years Rated flow Actual flow Estimated Energy savings rate, gal/mim rate, gal/min energy use per with low flow household 2.5 gpm kWh/yr 1994 to 2.5 1.7 1,128 present 1980 - 1994 3.0 2.0 1,328 200/$34* Pre 1980 5.0 – 8.0 4.3 2,855 1,727/$294* * Based on average 17 cents per kWh tier two Source: NRDC “Energy Down the Drain” 2004
- 27. Combining Water Harvesting with Indoor Conservation
- 28. Water Harvesting Benefits • Saving water saves energy and reduces air pollution • The more than 60,000 water systems and 15,000 wastewater systems in the United States • are among the country’s largest energy consumers, using about 75 billion kWh/yr • nationally—3 percent of annual U.S. electricity consumption • Energy intensity = energy required to use a
- 29. Greywater replenishes groundwater & enhances soil fertility
- 30. Designing a Greywater System • Minimum irrigation area (code) • Actual greywater production • Soil and percolation rate, slope • Plant choices and water requirements
- 31. Soil Texture
- 32. Largest minimum area = 192 sq ft/ 160 gal/ day
- 33. Estimating Greywater Production Fixture GPM Uses/day Occupants Gal/day Lav faucet 2.5 5 each 2 12.5 0.5 min Shower 2.5 1 each 2 40 8 min Clothes 20 gal 0.65 8.5 washer per load Total 61 gal/day Weekly 427 Yearly 22,186
- 34. Sizing Greywater Irrigation Area: Summary • By code 3 bdrm house 160 gal/day; 1,120/wk • Maximum area for minimum requirement (clay soil) = 192 sq ft/160 gal • More typical ~ 350 - 700 gal/wk • Can irrigate ~ 7 - 15 trees and shrubs (500 – 800 sq ft)
- 35. Plant Considerations • Fruit trees and ornamentals best citrus, banana, apple, plum, guava • Groundcovers and turf with dripperline • Laundry soap cautions
- 36. Code and Permit Issues • 1603A.1.1 Clothes Washer System (may be installed without a permit if in compliance) • Follow 12 guidelines; don’t alter existing plumbing • May not result in ponding or run-off • If released above-ground requires >/= 2” mulch • Minimize contact • Operations & maintenance manual • Permit triggers: cutting pipe, using pumps, >250 gallons/day
- 37. Laundry to Landscape • Indoor plumbing • Outdoor piping • Test, “tune”, label
- 38. 3-Way Valve & Washer Hose
- 41. More Complex Systems • Greywater stub outs • Whole house • Constructed wetlands • Non potable indoor use
- 42. Greywater Stub outs • Greywater stub outs enable greywater distribution systems to be installed later • Lowers economic hurdle for occupancy • Stub out may be in anticipation of new system types
- 43. Whole-house Greywater System for Irrigation including 3,000 gallon Rainwater Cistern
- 45. Water treatment: Constructed Wetland
- 46. Cost Benefit Summary System Cost (Range) Gallons Saved Per Year Laundry to Landscape $500 - $2,500 2,000 - 10,000 Branched Drain $1,000 - $3,000 15,000 - 30,000 (showers) Whole house $4,000 - $7,000 35,000 - 60,000 Pump/dripperline Whole house > $5,000 35,000 - 60,000 wetland