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.

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

6. Rainwater Harvesting

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

12. Urban Rainwater Harvesting

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