The Department of Ecology is clarifying regulations governing the collection and use of rainwater in Washington state. Currently, homeowners aren’t required to obtain water right permits to collect and store small amounts of rainwater. The new rule for the

first time would define how much rainwater can be collected and used before a permit is required.

The rule isn’t intended to regulate storage and release of rainwater when no “beneficial use” will be made of the water. Under state law, beneficial uses include recreation, irrigation, residential water supplies and power generation.

Washington law identifies rainwater as a water resource of the state. Residential rainwater collection systems can range from a

50-gallon rain barrel to cisterns of 30,000 gallons or more. Commercial systems can be much larger. Ecology is seeking public comment on what the threshold should be for requiring a water right permit for those systems that could affect the water supply of senior water right holders or stream flows in some river basins.

Non-potable uses of rainwater typically include toilet flushing and irrigation for gardens. In water-short areas such as the San Juan Islands, some homeowners use rainwater as the sole source of their water supply. Ecology is especially interested in encouraging rainwater collection in urban areas like Puget Sound where it can be used to reduce stormwater runoff and supplement municipal water supplies.

“A statewide rule would remove the ambiguity about rainwater collection from existing water law,” said Ken Slattery, manager of Ecology’s Water Resources Program. “We want to ensure that collection and storage of rainwater happens in a way that is consistent with the protection of stream flows and water rights.”

Beginning this fall, island-wide water right permits will be issued in San Juan County where some island residents use rainwater for their water supply.

Read more about rainwater collection at Ecology’s new rainwater website: http://www.ecy.wa.gov/programs/wr/hq/rwh.html