Water Harvesting for Landscape Irrigation

Rosalind Haselbeck & Rich Alianelli

Building Green Futures Inc. CCSE

April 19, 2012

Introduction: Who we are

Water Run-off: developed vs. natural

Source: http://www.coastal.ca.gov/nps/watercyclefacts.pdf

Water Use, San Diego

http://www.savewateroceanside.com/conservationtips.asp#graph

Rainwater Harvesting

Components of Rainwater Harvesting for Irrigation

Roof catchment area

Gutters & downspout

Storage

Tank

Overflow Pump

To drip system/hose

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

Estimating Supply & Demand

Source: Building Green Futures (www.buildinggreenfutures.com)

Above-ground Tanks

Source: RainHarvest Systems

Source: BH Tanks Inc. Source: Bushman Tanks USA

Source: Tankworks Australia

Below-ground Tanks

Source: Graf Rainwater Tanks

Source: Rainwater Collection Solutions

Source: Xerxes Fiberglass Tanks

Source: Atlantis Water Management

Urban Rainwater Harvesting

A Rainwater Pillow

Source: Building Green Futures (www.buildinggreenfutures.com)

Source: Building Green Futures (www.buildinggreenfutures.com)

2) 8,500 gallon

below-ground

system with a

geothermal loop

field and barrels

above ground

Underground Rainwater Storage:

8,000 gallons in Graf Carat

Tanks

Corrugated

steel tank with

10,000 gallon capacity

Using Earthworks

Greywater Recycling

• Background

• Clothes washer systems

• Whole house systems

• Constructed wetlands

• Indoor non-potable

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!

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

Defining Greywater

• Greywater = Washwater

• Excludes toilet wastes and kitchen scraps

• Provides Phosphorus, Nitrogen, Potassium

• Greywater systems are onsite wastewater treatment systems using subsurface irrigation

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

Energy Down the Drain

Source: NRDC “Energy Down the Drain” 2004

Energy intensity = energy required to use a

specific amount of water in a specific location

water heaters

pump stations

pressurizing water

(car wash

Energy Savings with Low Flow Shower Head

Years Rated flow rate, gal/mim

Actual flow rate, gal/min

Estimated energy use per household kWh/yr

Energy savings with low flow 2.5 gpm

1994 to present

2.5 1.7 1,128

1980 - 1994 3.0 2.0 1,328 200/$34*

Pre 1980 5.0 – 8.0 4.3 2,855 1,727/$294*

Source: NRDC “Energy Down the Drain” 2004

* Based on average 17 cents per kWh tier two

Combining Water Harvesting with Indoor Conservation

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 specific amount of water in a specific location

Greywater replenishes groundwater

& enhances soil fertility

Designing a Greywater System

• Minimum irrigation area (code)

• Actual greywater production

• Soil and percolation rate, slope

• Plant choices and water requirements

Soil Texture

Largest minimum area = 192 sq ft/ 160 gal/ day

Estimating Greywater Production

Fixture GPM Uses/day Occupants Gal/day

Lav faucet 2.5 0.5 min

5 each 2 12.5

Shower 2.5 8 min

1 each 2 40

Clothes washer

20 gal per load

0.65 8.5

Total gal/day

61

Weekly 427

Yearly 22,186

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)

Plant Considerations

• Fruit trees and

ornamentals best citrus, banana, apple,

plum, guava

• Groundcovers and turf with

dripperline

• Laundry soap cautions

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

Laundry to Landscape

• Indoor plumbing

• Outdoor piping

• Test, “tune”, label

3-Way Valve & Washer Hose

More Complex Systems

• Greywater stub outs

• Whole house

• Constructed wetlands

• Non potable indoor use

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

Whole-house Greywater System for Irrigation

including 3,000 gallon Rainwater Cistern

Water treatment: Constructed Wetland

Cost Benefit Summary

System Cost (Range) Gallons Saved Per Year

Laundry to Landscape $500 - $2,500 2,000 - 10,000

Branched Drain (showers)

$1,000 - $3,000 15,000 - 30,000

Whole house Pump/dripperline

$4,000 - $7,000 35,000 - 60,000

Whole house wetland

> $5,000 35,000 - 60,000