Rainwater harvesting consists of the collection of rain in rooftop or ground vessels so that the water can be used in irrigation when needed or shunted to a safe water source for indoor use. Collected rainwater, along with gray water and reclaimed water, represents an alternative water source that helps reduce overall household water bills by 25 percent. Gray water is the excess water that runs into household drains connected to sinks, showers, bathtubs, and washing machine rinse cycles. (Blackwater comes from the same sources, plus toilets, and represents any wastewater expected to contain disease-causing microbes.) Water conservation systems pump gray water to holding tanks for later use in irrigation. Reclaimed water is water that has been treated for uses other than drinking, such as treated wastewater from dishwashers.
Rainwater collection systems use gravity to do the work, making these systems easy to use and inexpensive. Rainwater collects into large cisterns, barrels, or rooftop tanks connected to a downspout that carries it to a holding tank on or under the ground. The few precautions that should be taken in managing rainwater collection systems are the following:
- a cover to prevent entry of animals or mosquito breeding
- fencing or other security measures to prevent small children from falling in
- state-by-state differences in laws regarding the use of rainwater
Alternative water sources additionally play a role in xeriscaping by making use of almost every drop of water in an area to both aid the environment and conserve water use and costs.
