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Get answers to important questions about recycled water.

Using recycled water is good for our region:

  • It saves drinking water for drinking and leaves water in rivers for fish and other wildlife.
  • It reduces the amount of treated wastewater that we send to Puget Sound and puts that water to better use. The Washington State Department of Natural Resources requires King County to offer recycled water.
  • It creates water supply options for our region, creating resilient water supplies for our community to deal with drought and climate change.

After traditional wastewater treatment, King County uses advanced filters to create recycled water. We use membrane filters at Brightwater and Carnation and sand filters at South Plant. We disinfect recycled water using a strong form of household bleach or ultraviolet light (at Carnation). We closely monitor and rigorously test recycled water before delivering it to our customers.

King County’s recycled water is used for irrigating food crops, athletic fields, golf courses, tree farm, nurseries, and natural vegetation restoration sites. It is also used for toilet flushing and cooling systems in buildings.

Recycled water is distributed through separate pipes so it is not mixed with the drinking water supply. Purple is the official color for recycled water pipes through-out the world. Recycled water pipes and plumbing fixtures (like sprinkler heads) are purple. Purple signs tell people not to drink the water.

King County does not treat recycled water for drinking. But many other places do. In California and many other places, advanced treatment technologies like reverse osmosis create drinking-quality water from recycled water.

Recycled water is used on organic crops in Washington State and meets USDA organic standards.

Even irrigators who currently have a right to use water from a river, lake, or groundwater can work with on King County on cost-effective pricing. The State of Washington has programs that allow irrigators to use recycled water and preserve their legal water rights. The following websites have information and guidance: