P1251328611Mteyr

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RAINWATER HARVESTING Going beyond the rain barrel
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Benefits of rainwater harvesting
1 inch of rain on a 1,000 ft2 roof yields 620
gallons of collected rainwater
Decreases use of municipal or well water also
saves energy Helps in stormwater management
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How much of a difference can it make?

• For a family in a 1,500 sf house, rainwater
  harvesting can supply about 20 of household
  demand or 39,000 gallons of water annually

This percentage can be GREATLY increased with
water-saving fixtures
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How much of a difference can it make?
Between 2000 and 2007, the number of housing
units in VA increased by 0.36 million units. If
all of these units had rainwater harvesting
systems, they could supply 14 billion gallons of
harvested rainwater annually, enough for all of
the water used by the city of Virginia Beach
http//factfinder.census.gov/servlet/GCTTable?_bm
y-geo_id01000US-_box_head_nbrGCT-T9-R-ds_name
PEP_2007_EST-formatUS-9Sh
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Making a difference beyond water conservation

• Rainwater harvesting also decreases overland
  flow, in turn decreasing the delivery of
  non-point source pollutants to surface waters

F. Lamiot, July 2005, available Wikimedia commons
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Making a difference beyond water conservation

• If all of the new housing units had rainwater
  harvesting systems, nutrient runoff could be
  reduced by
• 38 kg of Total Phosphorus per day
• 290 kg of Total Nitrogen per day
• based on average TP and TN concentration in
  residential runoff from Schueler, 1987

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Putting it in context with point source
discharges
Twenty-five significant point source discharges
in the Rappahannock River Basin are identified
with allowed total nutrient allocations. The
possible reduction in Total N and Total P from
rainwater harvesting systems on all new housing
units equals 66 of the TP 38 of the
TN allowed from the point source discharges.
http//leg1.state.va.us/cgi-bin/legp504.exe?000re
g9VAC25-720-70
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Making a difference beyond water conservation

• 3 of national energy consumption goes to water
  and wastewater services(56 billion kilowatt hours
  (kWh)
• 45 million tons of greenhouse gases
• http//www.epa.gov/waterinfrastructure/bettermanag
  ement_energy.htmlbasicone

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Making a difference beyond water conservation

• 1 kWh of energy is needed to treat and transport
  667 gallons of municipal drinking water
• 1 kWh of energy can pump 960 gallons of rainwater
• For a single house, rainwater harvesting can save
  18 kWh per year

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IF ALL OF THE NEW HOUSING UNITS USED RAINWATER
HARVESTING, IT WOULD HAVE THE CARBON EQUIVALENT
OF TAKING 843 CARS OFF THE ROAD
EACH CAR REPRESENTS 7 CARS
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Possible uses of rainwater

• Outdoor uses
• Indoor non-potable uses
• Toilet flushing
• Laundry
• Cooling
• Indoor potable uses
• Drinking
• Bathing
• Cooking, etc.

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Who regulates the use of rainwater?
EPA? Department of Health? Department of
Conservation and Recreation? State Water Control
Board? Department of Environmental Quality? Local
plumbing inspector? USDA?
Environmental impact
Human health
Building code
Yes to all!
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How to encourage rainwater harvesting

• Legislative
• Require rainwater harvesting systems
• Remove barriers to rainwater harvesting systems
• Clearly define appropriate uses
• Define applicability for stormwater
• Define system requirements
• Market-based
• Increasing water rates
• Stormwater fees

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Payback analysis
Office building Location Loudoun County,
VA Roof area 98,000 sf Rainwater use
Toilets/urinals GPD 10,800
80,000 gallon tank supplies about 1.8 million
gallons of water per year
Yearly savings 3,409 based on current water
rates
System costs approximately 150,000
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Payback analysis
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Other ways to improve payback

• Stormwater fees
• Offsetting capital costs by reducing traditional
  stormwater practices
• Innovative design

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Is rainwater harvesting worth promoting?

• For the office building in Loudoun, the 80,000
  gallon tank would reduce runoff from the roof by
  75

Nitrogen and phosphorus equivalent of almost 100
pounds of fertilizer per year Over 1,000 pounds
of sediment per year
http//www.stormwatercenter.net/
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Case Study Residential
Charlottesville, Virginia
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Case Study Residential

• 3,400 gallon underground storage
• Subsurface irrigation

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Case Study Residential
Franklin County, Virginia
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Case Study Residential
3,400 gallon underground storage Water used for
irrigation Prevented water runoff into the lake
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Case Study Multi-family
Charlottesville, Virginia
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Case Study Multi-family
1500 gallon aboveground storage Urban farm
irrigation
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Case Study Commercial
Downtown Roanoke, Virginia
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Case Study Commercial
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Case Study Commercial
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Case Study Commercial

• 10,000 sq.ft. roof line
• 5,000 gallon storage
• Water used to flush toilets
• LEED Certified Project

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Case Study Industrial
Roanoke County, Virginia
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Case Study Industrial
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Case Study Industrial

• Less environmental impact post construction
• 120,000 gallon storage
• Water used to wash inmates clothes
• LEED Certified Project

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Case Study Industrial
Radford, Virginia
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Case Study Industrial

• Converted detention pond to retention pond
• Before used 20,000 gallons/day of potable water
  for cooling towers
• Water used for cooling towers irrigation

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Case Study Commercial
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Case Study Commercial
10,000 gallons of storage UV light filtration
system Harvested rainwater used for fire
suppression and to wash vehicles and flush toilets