The National Resources Defense Council
Capturing Rainwater from Rooftops
The National Resources Defense Council has released a 25-page report on Capturing Rainwater from Rooftops. The report finds, “Rooftop rainwater capture is a simple, cost-effective approach for supplying water that promotes sustainable water management.”
Benefits of rainwater harvesting include:
- Inexpensive, on-site supply of water that can be used for outdoor non-potable uses with little, if any, treatment, or for a variety of additional uses including potable supply with appropriately higher levels of treatment
- Reduced (or no) energy and economic costs associated with treating and delivering potable water to end users because capture systems often use low-volume, non-pressurized, gravity fed systems or require only the use of a low power pump for supply
- Reduced strain on existing water supply sources
- Reduced runoff that would otherwise contribute to stormwater flows, a leading cause of surface water pollution and urban flooding
Some statistics from the report:
- 270 billion gallons of water are used each week—a significant portion of it potable—to water 23 million acres of lawn in the United States. This watering bill costs $40 billion annually.
- One study shows that the total annual volume of rainwater falling on rooftops in eight U.S. cities, if captured in its entirety, would be enough to meet the water supply needs of between 21% and 75% of that city’s population each year.