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King County Washington home

Our treatment facilities

Learn about King County's wastewater and wet weather treatment facilities that protect water quality and public health in the central Puget Sound region.

Our wastewater treatment facilities effectively clean dirty water collected from our local sewer agencies while recovering valuable resources. We’re also committed to being a good neighbor and having a positive impact on the communities we serve. Learn more about our wastewater system and service area.

Learn how we promote equity and social justice and sustainability at all our facilities.

Regional wastewater treatment plants

aerial view of the Brightwater Treatment Plant

Brightwater Treatment Plant

A group of people in orange vests and hard hats tour the South Treatment Plant

South Treatment Plant

An aerial view of West Point Treatment Plant

West Point Treatment Plant

Local wastewater treatment plants

A view of the Vashon Treatment Plant with the administration/Operations building next to the treatment facilities

Vashon Treatment Plant

An aerial view of the Carnation Treatment Plant

Carnation Treatment Plant

CSO treatment facilities

An aerial view of a typical CSO treatment facility

View CSO treatment facilities

Related topics

About the Wastewater Treatment Division

Our regional wastewater treatment system has a big job to do. Not only does it operate around the clock to sustain a healthy environment, this vital infrastructure supports economic development that enables our region to thrive.

Sewer system services

Services to support the regional wastewater conveyance and treatment system.

Capital projects

Find information on King County’s current and planned wastewater capital projects, including project descriptions, locations, and status, and sign up for project updates. 

Education and community

King County provides educational experiences for all ages, spaces for community events, and places to enjoy nature.

Wastewater programs

Learn about our programs to improve water quality, plan and prepare our wastewater system for regional growth, and protect public health and the environment.

Resource Recovery

Learn how Resource Recovery provides leadership around sustainability and the reuse of valuable products to support the mission of the Wastewater Treatment Division to protect public health and the environment.