Recycled Water


Recycled water is highly treated wastewater that has been filtered and disinfected to remove solids and other impurities. Simply put, recycled water is water that is used more than once! 

Recycled water is used across the country (i.e. California, Florida, Arizona) and internationally as a sustainable water source to irrigate food crops, but is underutilized and underdeveloped here in Washington state. More irrigation use of recycled water would reduce river water withdrawals, protecting salmon and other wildlife that depend on cool and clean water. 

The Driver to Use Recycled Water

Many of our states rivers and streams are overdrawn by out of stream uses during the late summer when flows are absolutely vital for the species survival of Salmon, steelhead and other aquatic species. Demand for freshwater resources in Washington is outgrowing availability. This availability is exacerbated by climate change, increased demand from population growth, and limits to new water rights. 

These conditions compel a new way of thinking about agricultural production and irrigation sources, for the health of rivers, and climate resilient and sustainable agriculture.

A Sustainable Water Source

Irrigating with recycled water in specific basins can serve as a vital tool to protect flows for salmon, relieving rivers of agricultural surface diversions. 

Recycled water irrigation is already standard practice in some regions of the United States, including California’s Salinas Valley where it has been used to irrigate fruits and vegetables since 1998, providing more than 90% of the irrigation supply. In Washington state, recycled water has yet to be fully realized as a water source for food crops. 


Active Projects

Sammamish Valley Recycled Water Project

Tapping into a Sustainable Water Source of Water for Agriculture

The Sammamish Valley Recycled Water Project aimed to evaluate perceptions and address concerns about the safe use of recycled water on food crops and to reduce the reliance on the Sammamish River for irrigation. More irrigation use of recycled water would reduce river water withdrawals, protecting salmon and other wildlife that depend on cool and clean water.

Although recycled water is strictly regulated, there is growing concern about trace amounts of unregulated chemicals in recycled water that might be exposed to people and the environment. These chemicals, known as contaminants of emerging concern or CECs, come from various products we use every day, like medicines, shampoos, food packaging, drinks, and clothing.

Click on the tabs below to learn more about each project component!

Project Components

To learn more about how King County uses recycled water, visit their website.

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Sammamish Valley Recycled Water Project Partners and Funders are working together to re-water Washington rivers and streams. 

Project Partners

Washington Water Trust

King County Recycled Water

Washington State University Puyallup Extension

Project Funders

King Conservation District

Bullitt Foundation

King County WaterWorks