Rainwater Harvesting

Above-ground cistern collects rainwater'Rainwater Harvesting' refers to the collection and storage of rain. Collection is usually from rooftops, and storage in catchment tanks. Stored water can be used for non-potable purposes such as irrigating lawns, washing cars, or flushing toilets. Rainwater harvesting systems can range from a simple barrel at the bottom of a downspout to multiple tanks with pumps and controls. Before the creation of public water utilities, rainwater harvesting provided water for many American homes. It is still popular in places with limited water resources such as island communities like Hawaii. While we think of ourselves as living in a rainy climate, recent drought conditions throughout Oregon remind us how quickly we can run short of water.

Using purified potable water for purposes like flushing toilets or irrigating landscape is a waste of a valuable resource. Portland residents are asking more questions about the role of conservation in extending the supply of drinking water. Stored water can substitute for piped drinking water for many uses where a high level of purity is not required.

Rainwater harvesting is also effective in reducing stormwater runoff pollution. When rain falls, it is clean, but it immediately picks up pollutants from rooftops and pavement. This pollution is carried into storm drains and then into streams. Collecting stormwater from rooftops and directing it to storage tanks so it can later be used for irrigation or flushing decreases the volume and rate of runoff. 

For more detailed information, check out Rainwater Harvesting for Drylands and Beyond by Brad Lancaster.