As adequate water supplies become less reliable it makes sense to optimize use of the clean water that is available. Rainwater harvesting is a low-cost way to do so. It is a simple technology; easily installed and easily maintained. Very simple systems collect rainwater to use for watering gardens and landscaping. By adding a treatment system, rainwater can be harvested as drinking water.
According to USDA, over 40 percent of the United States is currently experiencing severe, extreme or exceptional
drought conditions, and almost half of the country is experiencing drought. No areas are immune. Extreme and exceptional drought stretches from the normally moist mid-Atlantic and Smokey Mountain regions to the normally arid Midwest and southwest. In many areas, underground fresh water aquifers are being drawn down faster than they can be replenished.
Rainwater harvesting can be valuable throughout the U.S. As the population density increases and the weather becomes less predictable a rainwater harvesting system will add value to any new or existing property.
A complete rainwater collection system includes:
A catchment area (roof or paved area)
A conveyance system (gutters and leaders), and
A holding system (cisterns, tanks or ponds).
Except for the holding system, the other elements are part of all houses. The holding system can be as simple as a used 55-gallon drum at the bottom of each downspout, or as complicated as a cast-in-place concrete cistern. Open holding tanks of any kind should be covered with a screen to control mosquitoes.
This simplest of systems would require the stored water to be used below the level of the holding system, and the harvested water would flow by gravity. Otherwise, a delivery system (pumps) would be necessary. If the rainwater were to be used for drinking, a roof-wash system to divert the first 10-20 gallons away from the system as the collection surface is flushed clean and a treatment system (filters and/or purifiers) would be required.
For more information about rainwater harvesting, consult these sites:
Texas Guide to Rainwater Harvesting
Greenbuilder's Sourcebook on Harvested Rainwater
American Rainwater Catchment Systems Association (ARCSA)
For field evaluations:
Chapman Companies: Rancho San Marcos, Santa Fe, New Mexico
Content updated on 5/18/2009