rainwater harvesting - green infrastructure

8/9/2019 Rainwater Harvesting - Green Infrastructure

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Rainwater Harvesting

U.S. Water Supply

Universal access topotable water supplies.

World’s highest per capitause – approximately twicethat of Europe.

Cost of water is amongthe lowest in the world. 0.07¢ - 0.4¢ per gallon Ö

70¢ - $4 per 1,000 gallons Average cost nationally

approximately $2 per 1,000gallons



U.S. Water Supply (cont.)

Population growth &developmentincreasing demand.

Sustained droughts inSoutheast &Southwest.

Climate change maydecrease snowpackand introduce drier climate.

Water managers in 36states anticipate water shortages.

Prettyboy Reservoir, Maryland during 2002 drought.Photo courtesy of National Weather Service.

Domestic Water Use

Typical Domestic Daily per Capita Water Use.

Use Gallons per Capita % of Daily Total

Potable indoor uses Showers Dishwashers Baths Faucets Other uses, leaksSubtotal

11.61.01.210.911.135.8

7.0%0.6%0.8%6.6%6.7%

21.7%

Non-potable indoor uses

Clothes washers ToiletsSubtotal

15.018.533.5

9.1%11.2%20.3%

Outdoor uses 95.7 58.0%American Waterworks Association Research Foundation (AWWARF), Residential

End Uses of Water , Denver, CO, AWWARF, 1999.



Commercial Water Use

Typical Daily Water Use for Office Buildings and Hotels.

Use Office Buildings% of Daily Total

Hotels% of Daily Total

Potable indoor uses

Showers Faucets Kitchen Other usesSubtotal

---1%3%

10%14%

27%1%10%19%57%

Non-potable indoor uses Toilets/urinals Laundry

CoolingSubtotal

25%---

23%48%

9%14%

10%33%

Outdoor uses 38% 10%Pacific Institute, Waste Not, Want Not: The Potential for Urban Water Conservation

in California, November 2003.

Current Conditions Non-potable uses constitute

a large percentage of demand.

Disparity between “high-quality” water supply andlarge percentage of “low-quality” demand.

Inefficiencies propagated byinadequate pricing andcontinuation of familiar

practices. Building and plumbing codes

often necessitate potablewater use throughout abuilding or residence.



Water Pricing

Inexpensive cost of water creates little incentivefor conservation.

GAO found insufficient funding in 29% of water utilities to cover cost of providing service.

Water demand is relatively inelastic – increasedprices have limited effect on use but canencourage supply substitution.

Full cost pricing is one of EPA’s four pillars of

sustainable infrastructure – ideally accounts for externalities in addition to capital and O&M costs.

Rainwater Harvesting Collecting roof rainwater

in rain barrels or cisternsfor later reuse.

Residential andcommercial applications.

Ideal for outdoor and non-potable indoor uses.

Can be used for potableuses with proper treatment.

Chicago Center for Green Technology.Photo courtesy of Farr Associates.



Rainwater Harvesting Benefits

Provides inexpensive supply of water.

Augments drinking water supplies.

Reduces stormwater runoff and pollution.

Reduces erosion in urban environments.

Provides water that needs little treatment for irrigation or non-potable indoor uses.

Helps reduce peak summer demands.

Helps introduce demand management for drinking water systems.

Water Supply & Energy Demand

Estimated Energy Consumption for Water Treatment and Distribution.

ActivityEnergy Consumption

kWh/MG

Northern CA Southern CA National Avg.

Supply andconveyance

150 8,900 ---

Water Treatment 100 100 ---

Distribution 1,200 1,200 ---Total 1,450 10,200 250

California Energy Commission, California Water – Energy Issues, Public Interest Energy ResearchProgram, Presented at the Western Region Energy – Water Needs Assessment Workshop, Salt LakeCity, Utah, January 10, 2006.



Water Supply & Energy Demand (cont.)

Reducing water demand 10% could save293 billion kWh of electricity each year.

Energy costs account for 80% of typicalwater bill.

Energy accounts for 1/3 of utility operatingcosts.

7 to 8% of national energy consumption tiedto treating and distributing water.

Michael Nicklas, Rainwater , High Performance Buildings, Summer 2008.

G. Tracy Mehan, Energy, Climate Change, and Sustainable Water Management , EnvironmentReporter, 2007.

Water Supply & CO2 Emissions

Carbon Dioxide Emissions from Electric Power Generation.

Fuel Type

CO2 OutputRate

PoundsCO2/kWh

CO2 Output per MGWater Delivered

(x 1,450 kWh)Northern CA

CO2 Output per MGWater Delivered(x 10,200 kWh)Southern CA

CO2 Output per MGWater Delivered

(x 250 kWh)National Avg.

Coal 2.117 3,070 lbs 21,600 lbs 530 lbs

Petroleum 1.915 2,775 lbs 19,500 lbs 480 lbs

Natural gas 1.314 1,905 lbs 13,400 lbs 330 lbsU.S. Department of Energy and U.S. EPA, Carbon Dioxide Emissions from the Generation of Electric Power in the United States,July 2000.



Los Angeles Water Supply

Demand of 500 MGD.

Approximately 445 MGDsupplied by Los Angeles,California, and ColoradoRiver Aqueducts.

4.6 million kWh are useddaily to deliver water viaaqueducts.

If natural gas is fuel for

power plants – 3,000 tonsof CO2 emitted each dayfor water delivery.

California Aqueduct.

King Street Center – Seattle, WAWater Conservation

Rainwater Harvesting

Over 16,000 gallons of storage at 327,000 ft2

King Street Center usedfor toilets and irrigation.Provides 60% (1.4million gallons) of toilet

flushing water annually. CO2 reduction of 700 lbs.

King Street Center.



The Solaire - Battery Park City, NY

Required 2.4 inches of rainwater retention.

10,000 gallon cistern inbasement.

Rainwater treated withsand filter and chlorine prior to use for irrigatingtwo green roofs.

Treated and recycledblackwater used for toilet flushing and make-up water.

50% decrease in potablewater use. The Solaire. The first green U.S.

residential high rise.

Chesapeake Bay Foundation HQ

Rainwater collected in 3exposed cisterns.

Building uses compostingtoilets.

Rainwater treated with sandfilter, chlorine, static mixer,and carbon filter.

Reused water used for bathroom and mop sinks, gear washing, irrigation, fire

suppression, and laundry. 90% decrease in potable

water use. 73% of water used in building Philip Merrill Building cisterns. Photo: Chesapeake

from cistern system. Bay Foundation.



Stephen Epler Hall – Portland, OR

62,500 sf mixed-usestudent housing.

Rainwater used for visualaesthetic – roof runoff isdiverted to river rock“splash blocks” in publicplaza and then to planter boxes.

Effluent from planter boxescollected in undergroundcisterns.

UV used to treat water prior to use for toilet flushing on

first floor and irrigation. Saves over 100,000

gallons of potable water each year.

Epler Hall, PSU.

NRDC – Santa Monica, CA Cisterns installed

beneath planting beds. Collected rainwater is

added to graywater collection system andused for toilet flushingand irrigation.

Building uses duel-flush toilets, waterlessurinals, and drought-tolerant plants.

60% reduction inpotable water demand.

Cisterns at NRDC Santa Monica, Office



Rainwater Harvesting Considerations

Important to establish guidelines or codes –instances where rainwater governed by reclaimed water guidelines because of lack of adequate definitions.

Principles of rainwater harvesting apply equallyto graywater reuse – concept of matching qualityof supply to quality of demand.

Appropriate water pricing important to consider for adequate funding and resource valuation.

Portland Code

Defines rainwater harvesting uses for water closets, urinals, hose bibbs, andirrigation.

Establishes treatment and materialrequirements for collection and plumbingsystems, including labeling and pipe color.

Defines inspection and maintenancerequirements and responsibilities.



San Francisco MOU

Entered into in June 2008.

Establishes responsibilities for SF PublicUtilities Commission, Department of Building Inspection, and Department of Health.

Defines uses and treatment requirementsfor rain barrels and cisterns.

Codes: Know Your Audience



www.epa.gov/greeninfrastrucure

rainwater harvesting - green infrastructure

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