Harvesting Rainwater by Not Letting It Go to Waste

NPR 10 Jan 08;

Big rains slammed the West this week — big news in a region that has gotten used to dry weather.

Now some city governments are looking to rain to ease their water woes.

Thousands of years old, the concept is catching on in drought-prone areas, including Tucson, Ariz., where Brad Lancaster lives. He's the author of Rainwater Harvesting for Drylands and Beyond.

As Lancaster explains, harvesting rainwater means to "capture the rain as close as possible to where it falls, and then to use it as close as possible to where it falls."

The easiest method is to use the soil to capture the rainwater. "You create these bowl-like shapes in the landscape that collect water. You mulch the surface and plant them so the water quickly infiltrates, and then the plants become your living pumps."

"So you then utilize that water in the form of a peach, a pomegranate, an apple, wildlife habitat and beauty," Lancaster tells Renee Montagne.

A second, better-known version of rainwater harvesting is collecting rainwater from a roof in a tank, or a cistern.

The third example is harvesting wastewater, also known as graywater, from household drains, including showers, bathtubs, bathroom sinks and washing machines. (Other drains — such as the toilet, kitchen sink and dishwasher — are high in organic mater, such as food or bacteria, and are not suitable for reuse.)

Household wastewater is "an excellent source of rainwater that we can reuse to passively irrigate our landscapes in times of no rain," Lancaster says.

Lancaster says that 30 percent to 50 percent of potable water consumed by the average single-family home is used for landscaping. But nearly all of the irrigation water needs can be met just with rainwater and graywater, he says.

Rainwater harvesting can be useful even in areas that are not affected by drought, helping reduce flooding downstream, for example, Lancaster says.