Wastewater treatment

Learn about the process we use to clean wastewater at Brightwater.

53rd Avenue Pump Station upgrade

Get information about the Alki standby generator schedule, project need, and construction process.

Get information about the ESI 8 Rehabilitation Project schedule, project need, and construction process.

Find information about the Interbay Sewer and Odor Control Upgrade Project, including the project schedule and methods to upgrade the sewer pipes and control odors.

The Lower Duwamish Waterway is a working river that has supported Seattle’s economy for more than 100 years. Most of the pollution comes from past industrial practices and development decisions that would no longer be permitted today. These practices allowed contaminants to enter the waterway and settle into the sediment in the bottom of the river. The U.S. Environmental Protection Agency, or EPA, listed the river as a federal Superfund cleanup site in 2001 to address this historical pollution in the river sediment.

Learn more about why King County has a capacity charge, how the capacity charge is structured, and who pays the capacity charge.

Get information about the Coal Creek Sewer Upgrade Project schedule and design elements, including efforts to protect the Coal Creek Natural Area.

Learn about the design and sustainability features of the Georgetown Wet Weather Treatment Station and why King County embarked on the project.

Get information about the Lake Hills and NW Lake Sammamish Sewer Upgrade schedule and design elements, including efforts to protect the Coal Creek Natural Area.

Get information about the Lake Hills Sewer Relining project's schedule and construction benefits.

Find information about the Lakeland Hills Pump Station Replacement Project, including the project need and vision and the project schedule.

Get information about the M Street Trunk Rehabilitation schedule and design elements.

Get information about the North Mercer Island/Enatai Sewer Upgrade Project schedule and scope.

Get information about the Thornton Creek Basin Sewer Study and Upgrade schedule and design elements.

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.

Learn more about the West Duwamish Wet Weather Storage project schedule, need, and design elements.

Learn more about this upgrade project, combined sewer systems and how to find contract information.

Meet our education team and learn about our mission and vision. 

Get information about King County’s work on wastewater backup protection in South Park.

A description of the types of septage that are accepted and not accepted at the septage disposal facility.

Learn about the Wastewater Treatment Division Americans with Disabilities Act (ADA) Accessibility Program and accessibility standards implemented by the division.

New low-income housing in multi-family structures, single detached dwelling units, owner-occupied dwelling units, and shelter housing may qualify to receive a discounted capacity charge.

Enhancing the Alki Wet Weather Treatment Station and 63rd Ave Pump Station for reliability to protect Puget Sound.

King County Recycled Water customer resources and information.

King County prepares an annual report on its combined sewer overflow (CSO) control program for the Washington State Department of Ecology (Ecology).

The wastewater utility undergoes an annual audit to insure that its annual financial results are fairly stated and that all covenants with the utility’s bondholders have been met.

The annual meeting is for Septage Haulers to be informed of program requirements and updates. King County staff are available to answer questions.

The North Mercer Pump Station is located on Southeast 22nd Street and is the western point of the Mercer Island/Enatai Sewer Upgrade Project.

This area focuses on new sewer pipeline being installed under the North-Central Mercer Island residential streets. These include SE 22nd Street, SE 22nd Place, 78th Avenue SE, SE 24th Street, and 81st Avenue SE.

A 500 foot segment of new sewer pipe will be installed under North Mercer Way just east of the Mercer Island Park and Ride.

Some of the new sewer pipe will be installed underneath the I-90 Trail on Mercer Island. The trail will be closed in segments.

The new sewer line will run underneath 90th Place Southeast from Shorewood Drive to the cul-de-sac at the end of the road. We will also install below and above ground equipment to make pipe connections and for odor-control.

The new sewer line will run underneath streets, the I-90 Trail, and through a wooded area to the cul-de-sac on SE 35th Place. We will install below and above-ground equipment to help transition from a gravity sewer to a siphon.

Enatai Beach Park is a critical part of the sewer upgrade project. Three pipes meet here: a new pipeline that will cross under the East Channel from Mercer Island; the existing pipe that follows the shoreline up the Mercer Slough, and the new pipe that will be drilled under the Enatai hillside.

We are installing a new sewer pipe underneath the Enatai hillside between the Sweyolocken Pump Station and Enatai Beach Park and putting in a new lining on the existing pipe along Lake Washington between Enatai Beach Park and the mouth of the Mercer Slough.

Asset Management is the coordinated activity of an organization to realize the value from its assets. WTD manages over 60,000 assets valued at almost $5 Billion, including equipment like pumps and motors, infrastructure like pipelines and tanks, buildings, vehicles and technology, and software and databases.

King County built a new 85-inch siphon pipe under Salmon Bay between the Ballard and Interbay areas of Seattle to accommodate growth in north Seattle and reduce combined sewer overflows into Salmon Bay.

King County constructed 91 roadside rain gardens, a type of green stormwater infrastructure, on 15 blocks in the Sunrise Heights and Westwood neighborhoods in West Seattle.

Learn about the Barton roadside rain gardens, a green infrastructure project to control combined sewer overflows in West Seattle.

King County upgraded the aging Barton Street Pump Station to accommodate West Seattle’s growing population and ensure its safe and reliable operation for the next 50 years. The pump station is an underground facility located next to the Fauntleroy ferry landing in West Seattle. The pump station pumps wastewater to the Murray Avenue Pump Station which then sends flows to the county’s regional treatment plant at West Point in Seattle.

RainWise rebates cover most or all of the cost of installing cisterns and rain gardens on private properties in eligible combined sewer overflow basins.

Bellevue Pump Station upgrade & force main installation

Learn more about biosolids and how they return essential nutrients to soil for healthier, more productive farm crops and forest trees.

The Black Diamond Sewer Upgrade Project will increase capacity for 6 miles of regional sewer pipe in Black Diamond. The project will help us treat more wastewater to meet the needs of the growing Black Diamond community.

Information about King County’s project at the Brandon St. Regulator Station (RS) Overflow to address historical sediment contamination near County combined sewer overflow (CSO) outfalls.

The Brightwater Center and natural area features 3 miles of trails for you and your family to enjoy.

Find information and facts about Brightwater Treatment Plant located near Woodinville, including the treatment process, capital and improvement projects, and visiting the facility and grounds.

Find information and facts about Brightwater Treatment Plant located near Woodinville, including the treatment process, capital and improvement projects, and visiting the facility and grounds.

King County has built a new regional wastewater treatment system called Brightwater to serve the northern portion of the King County service area.

Information for industry-specific wastewater discharge requirements.

Information about King County Industrial Waste authorization for businesses that use septic tanks.

Information on the sewer capacity charge, how to pay your capacity charge bill, and who to contact if you have questions.

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

Find information and facts about Carnation Treatment Plant located in downtown Carnation, including the treatment process, improvement projects, and the nearby Chinook Bend Natural Area.

Information about King County’s project at the Chelan Ave. Regulator Station (RS) Overflow to address historical sediment contamination near County combined sewer overflow (CSO) outfalls.

CitySoil Farm is a 1.5-acre demonstration farm located at South Treatment Plant in Renton.

Find step-by-step instructions, guidelines, and safety information on how to clean up a sewage spill in your home.

Balancing the waterway's recreational, ecological and maritime uses will make the river healthier for people and wildlife.

The Coal Creek Sewer Upgrade Project will install new sewer pipes to carry more wastewater and meet the growing needs of Bellevue and Newcastle.

Find out how we’re helping develop the next generation of engineering leaders.

King County continues to improve water quality under negotiated changes in the consent decree with regulators to control sewer overflows during heavy storms as climate conditions worsen.

King County must control combined sewer overflows (CSOs) by 2037.

Check the map below to see if a combined sewer overflow, or CSO, is occurring before going swimming, wading, fishing, or boating near a CSO warning sign. These overflows take place within the City of Seattle.

View a list of recently completed wastewater capital projects. 

Learn how to take steps to address climate change in King County through heat energy reuse.

Tackling climate change is a priority for the Wastewater Treatment Division (WTD). We are working to reduce greenhouse gas emissions, support sustainable and resilient frontline communities, and prepare our wastewater system for the changing climate.

Information about construction dewatering requirements and authorization process.

Learn how King County Wastewater Treatment Division uses safe and sustainable construction methods.

Information about notification requirements to the Local Public Agency team prior to construction start and requirements regarding submittals and change orders during construction.

North Mercer Island/Enatai sewer upgrade construction status.

Staff contacts for the Wastewater Treatment Division education team.

Information about authorization for businesses that discharge contaminated stormwater into the King County sewer system.

King County and the City of Seattle are working together to control CSOs.

The Conveyance System Improvement (CSI) Program looks at ways to improve the King County wastewater conveyance system and address public health concerns, while ensuring that the system has sufficient capacity to respond to regional growth.

The Conveyance System Improvement (CSI) Program has been updated in 2004, 2007, and 2017. The next update is planned for 2027.

King County's CSO control program issues two documents for a comprehensive review of program successes, updates, and future projects. The reviews and updates are done in approximately five-year intervals.

Learn about King County’s combined sewer overflow facilities that treat a combination of stormwater and wastewater so it doesn’t discharge directly into our water bodies.

Learn more about projects that study biosolids and soil health done by independent and university researchers.

Learn how we are putting new and emerging technology to the test to assess how they would (or wouldn't) improve our performance.

Information about King County’s project at the Denny Way Regulator Station (RS) Overflow to address historical sediment contamination near County combined sewer overflow (CSO) outfalls.

Find information about dental wastewater discharge compliance in King County.

Detailed driving directions on how to get to the septage treatment facility at South Treatment Plant.

Information on the 2025 rates and fees to dispose of septage at the septage disposal facility at South Treatment Plant.

Information on what to expect when you get to the septage disposal facility, including the process of disposing of septage and amenities we offer at the facility.

What you can do to Protect Our Waters.

Wipes, tissues, paper towels, and other "unflushables" can create a sewer backup in your home – ew!

Learn about the Duwamish River Valley Groundwater Study that will help King County understand how groundwater in this coastal area is impacted by climate change, flooding, and tidal changes. 

Learn about the Duwamish River Valley Groundwater Study that will help King County understand how groundwater in this coastal area is impacted by climate change, flooding, and tidal changes. 

King County’s Wastewater Treatment Division and its predecessor Metro have worked for more than 40 years to restore the Lower Duwamish Waterway.

Information about King County’s project in the Duwamish/Diagonal area to address historical sediment contamination near County combined sewer overflow (CSO) outfalls.

East Waterway is part of the Harbor Island Superfund Site and is regulated by the U.S. Environmental Protection Agency (EPA).

Located in the Lake Hills Greenbelt Park in Bellevue

Eastside Interceptor (Section 13) Lining Project

The Eastside Interceptor Section 8 Rehabilitation Project will repair 4,800 feet of a 90- to 96-inch wastewater pipeline in Bellevue that is nearing the end of its useful life.

The Eastside Interceptor Section 8 Rehabilitation Project will repair 4,800 feet of a 90- to 96-inch wastewater pipeline in Bellevue that is nearing the end of its useful life.

The Wastewater Treatment Division provides a variety of water education resources that help you learn about our water systems.

The Wastewater Treatment Division offers free field trips for 3rd graders though 5th graders. 

King County is planning to upgrade the Elliott West Wet Weather Treatment Station (EWWTS). The upgrade will ensure compliance with stricter environmental regulations, meet the demands of a growing population, and handle a changing climate.

Information about the emergency disposal of liquid food-grade products.

Discover the important link between wastewater treatment and energy that helps King County meet its climate action goals.

Learn how our Energy Program is improving the energy efficiency of our wastewater treatment process and its operations.

Water and ecology: artists tell the story of Brightwater.

This page lists environmental documents prepared by the King County Wastewater Treatment Division that are currently available for public review and comment.

The King County Wastewater Treatment Division (WTD) strives to be a good neighbor to all communities.

We work in a variety of areas, from urban parks to shorelines to wetlands.

King County Recycled Water is safe to use for almost anything but drinking.

All data current for 2023, the most recent year for which data are available, unless otherwise noted.

Get answers to important questions about recycled water.

Monitoring wastewater flows is an important component of the Conveyance System Improvement (CSI) Program. 

Information about wastewater discharge authorization for food and beverage businesses.

Frequently Asked Questions (FAQ) about how King County is addressing historical sediment contamination near County combined sewer overflow (CSO) outfalls, including the County’s Sediment Management Plan (SMP).

King County has several projects planned at the Lakeland Hills Pump Station, including this backup generator installation and elevator replacement project to improve service to you and other residents in the Auburn area.

The Georgetown Wet Weather Treatment Station reduces water pollution and improves aquatic habitat and the overall water quality of the Duwamish River.

Make a difference by getting involved in your community.

Steps and information on how to get permitted to dispose of domestic (residential) and non-domestic (commercial) septage.

Information about authorization to discharge groundwater and stormwater into the King County sewer system.

Information about King County Industrial Waste Program approval for groundwater remediation sites.

Information about King County’s project at the Hanford and Lander Combined Sewer Overflows (CSOs) to address historical sediment contamination.

On Aug. 15, 2024, a pipe at the Heathfield Pump Station in Bellevue failed, sending wastewater into Vasa (Squibbs) Creek and Lake Sammamish. Following an emergency clean up and repair efforts, plans to fix the damaged pipe and restore the creek are ongoing.

The Wastewater Treatment Division offers free water education programs for high school students at our Woodinville and Renton facilities and in the classroom. Program descriptions are available below.

King County believes cleaning up the Lower Duwamish is the right thing to do. The County has worked for decades to restore the waterway by investing in habitat restoration, water quality improvement, pollution controls and sediment cleanups. These investments in pollution control and CSO reduction projects have successfully removed decades of contamination from some of the waterway's most contaminated areas.

Information about King County Industrial Waste hospital wastewater discharge authorization.

Learn how sewer heat recovery is a sustainable technology for King County.

Contact us for more information about whether your project is ready for King County Recycled Water.

Instructions on how to pay your capacity charge bill online or by mail.

Find out how you can play an important role in keeping our water clean and abundant.

When you flush the toilet or wash your hands in the sink, the water—referred to as “wastewater”—that travels down your drain flows into a system of pipes stretching across the region. The pipes carry the wastewater to a treatment plant to get cleaned before it can be released into regional water bodies.

Learn how King County finds and identifies sources of I/I and the methods and technologies we use to reduce or fix it.

Cleanups and wastewater controls alone are not enough to protect the Duwamish in the future – we all have a responsibility to do our part to prevent harmful chemicals from getting into our waterways.

Find information about the history and timeline of the I/I Control Program since its inception in 1999, including links to I/I technical reports and studies organized by year.

Find information about construction and improvement projects at Brightwater.

Wastewater Treatment Division staff are prepared to respond to a variety of complaints and incidents related to the regional wastewater conveyance and treatment system including addressing odor complaints, sewer spills, storm-related problems and other incidents.

Wastewater Treatment Division staff are prepared to respond to a variety of complaints and incidents related to the regional wastewater conveyance and treatment system including addressing odor complaints, sewer spills, storm-related problems and other incidents.

King County is working with our local sewer agencies to reduce and prevent infiltration and inflow (I/I) in our separated sewer system.

King County may use infrastructure such as storage tanks, pipes, and wet weather treatment stations to protect our waters.

The Interbay Sewer and Odor Control Upgrade Project will replace aging sewer pipes in Seattle’s Interbay neighborhood and add new odor control technology.

Learn about our work and the jobs needed to protect water and human health by applying for an internship or attending a career event.

King County's wastewater utility is entirely funded by the ratepayers who invest in our programs and services through their monthly rate and capacity charge bills. We take seriously our obligation to provide the highest levels of service and accountability to our ratepayers.

King County Wastewater Treatment Division is hiring. Get job notifications and learn what makes a good application.

Learn about diverse career opportunities in clean water services at the Wastewater Treatment Division, including our Operator-in-Training Program, Workforce Development Program and our Undergraduate and Graduate Intern Program.

The King County Wastewater Treatment Division provides a variety of water education programs that support teachers, schools, and our communities.

Keeping pollution out of the Lower Duwamish has been a regional priority since the 1950s.

The water we use inside homes and buildings and the rainwater that runs off the land all leads to the Puget Sound. 

King County installed new sewer lines and replaced aging pipes in Pacific, Algona, and Auburn. Work also included modifications at the Pacific Pump Station.

The annual report summarizes King County Industrial Waste's (KCIW) achievements in the areas of operations, special projects and activities, and public outreach.

Find King County Industrial Waste forms and permits downloads, current fees, and information about businesses that discharge wastewater into the King County sewer system.

Find information about King County Industrial Waste Program fees and surcharges.

The Industrial Pretreatment Newsletter contains information for those that discharge industrial wastewater to the King County sewer system or who are interested in the program.

Protecting our Waters is King County’s program to prevent pollution caused by excess stormwater in the sewer system on rainy days.

The Lower Duwamish Water Superfund cleanup builds upon decades of work by King County and its partners to improve water and sediment quality in the Lower Duwamish. The waterway is cleaner today than it has been in nearly a century.

Since 1999, the Regional Wastewater Services Plan (RWSP) has guided the programs and policies of King County’s wastewater system. The RWSP must be updated to address the next 30 years of our clean water services.

Information about King County’s project at the King Street Regulator Station (RS) Overflow to address historical sediment contamination near County combined sewer overflow (CSO) outfalls.

This project increased station pumping capacity, replaced aging equipment, and installed a larger diameter sewer force main to accommodate increased flows.

The Lake Hills and NW Lake Sammamish Sewer Upgrade Project will upgrade 4.5 miles of sewer pipes serving the growing Redmond and Bellevue area.

The Lake Hills Sewer Relining Project will install pipe lining along existing concrete pipe to prevent corrosion and extend the life of the pipe another 50 years.

The Lakeland Hills Pump Station Replacement Project will replace the aging Lakeland Hills Pump Station and build a new facility in Auburn to upgrade sewer services in south King County.

The Lower Duwamish Waterway Group (LDWG), a partnership between King County, the Port of Seattle, City of Seattle and The Boeing Company, has been actively cleaning up waterway pollution.

Learn how we use research and science to ensure Loop biosolids meet or exceed federal and state quality standards. 

Learn about clean water programs and careers with the Wastewater Treatment Division.

This page contains reports, studies, plans, glossary and other documentation for the Lower Duwamish Waterway Superfund Cleanup. 

King County provides wholesale wastewater treatment services to 18 cities, 15 local sewer utilities, and the Muckleshoot Indian Tribe in King, Snohomish, and Pierce counties.

Turn your dirt around

King County has completed construction of a new vehicle maintenance and staging facility in North Bend for transporting Loop biosolids.

The Lower Duwamish Superfund cleanup will enhance the health of the Lower Duwamish Waterway for tribes and community members, support a more thriving economy, and provide a healthier habitat for fish and wildlife. 

The M Street Trunk Rehabilitation Project will repair about 2.6 miles of deteriorated sewer pipes in the City of Auburn.

The M Street Trunk Rehabilitation Project will repair about 2.6 miles of deteriorated sewer pipes in the City of Auburn.

King County has repaired a section of corroded pipe at the intersection of M Street NE and 2nd Street NE in Auburn.

The Magnolia Wet Weather Storage Facility at Smith Cove is designed to store excess flows of stormwater and sewage. The facility’s 1.5 million-gallon underground storage tank will help keep sewage and stormwater out of Puget Sound during storms.

To prevent side sewer problems, know where your pipe is located, how old it is, and any known problems.  

Information about wastewater discharge authorization for medical and dental facilities.

Learn about water education programs for grades 6th through 8th graders. 

The Wastewater Treatment Division mission statement summarizes the reason for our existence and the purpose, or intention, behind our collective efforts.

Learn about King County’s efforts to develop wet weather facilities to control combined sewer overflows in the area of the mouth of the Duwamish River.

Learn about King County’s efforts to develop wet weather facilities to control combined sewer overflows in the area of the mouth of the Duwamish River.

King County completed construction on an underground storage tank (Murray Wet Weather Facility) near the Murray Pump Station in West Seattle. The tank is designed to contain up to 1-million gallons of stormwater and wastewater during heavy rains, which will protect public health and the environment by controlling combined sewer overflows that occur near Lowman Beach Park.

King County uses natural drainage to keep stormwater from entering the combined sewer system.

Information about flexible payment plans, payment deferrals for low-income seniors and disabled individuals, and discounts for eligible low-income housing residents.

How King County complies with the EPA's CSO control standards.

Information about King County’s project at the Norfolk Regulator Station (RS) Overflow to address historical sediment contamination near County combined sewer overflow (CSO) outfalls.

The wet weather storage facility is now operational. While the bulk of construction work was completed in December 2015, the contractor completed some work on the pump station site through early 2017. This included work on the new building, final landscaping and drainage improvements.

To avoid premature replacement of usable assets, King County performs inspections and condition assessments throughout the life of wastewater pipelines. King County carried out a project to evaluate the condition of the North Beach Force Main, installed in 1963.

The North Mercer Island/Enatai Sewer Upgrade Project will replace aging pipes serving areas in North Mercer Island and Bellevue near Enatai Beach, and the Town of Beaux Arts Village.

Information about odor and air quality standards and the Air Quality Advisory Board at the Brightwater treatment plant.

The King County Wastewater Treatment Division (WTD) provides relevant information on operational, financial, regulatory and safety performance of the utility. Much of this information is updated monthly.

Learn about the King County Wastewater Treatment Division’s Operator-in-Training Program, including the program outcomes, how to apply, and what to expect if you’re selected.

The King County Industrial Waste Program (KCIW) issues waste discharge permits to businesses discharging wastewater to the King County sewage system that are federally regulated with pretreatment standards. These “categorical” businesses include manufacturers and processors of metals, wastes, plastics, chemicals, batteries, electronics, pharmaceuticals, soaps, detergents and many others.

The King County government is a major property owner and a service provider in the Lower Duwamish area. We manage transit service, wastewater facilities, trails, health services, roads and bridges, and even an international airport. Our agencies are dedicated to enhancing the quality of life and protecting public health and the environment. We are proud to be both part of the community and a representative to the people who live and work there.

Find information about King County's regional wastewater conveyance and treatment system.

King County’s Wastewater Treatment Division and its predecessor Metro have worked for more than 40 years to restore the Lower Duwamish Waterway. King County is helping to pay for and implement EPA’s Superfund cleanup plan.

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

Learn about the Partners in Water (PiW) program that connects Wastewater Treatment Division (WTD) work groups with community organizations to advance mutually beneficial goals related to WTD operations and services.

King County conveys treated water to Puget Sound and to recycled water beneficial uses from its regional wastewater conveyance and treatment system under permits issued by the Washington State Department of Ecology (Ecology) and Washington State Department of Health.

Information about King County’s Sediment Cap and Enhanced Natural Recovery Area Remediation project at Piers 53-55 to address historical sediment contamination.

How King County is implementing its Sediment Management Plan (SMP) to address historical sediment contamination near County combined sewer overflow (CSO) outfalls.

Find instructions how to apply for the King County Sewer Heat Recovery Program.

The history and timeline of King County’s efforts to address historical sediment contamination near County combined sewer overflow (CSO) outfalls, including key milestones of the cleanup.

This page lists documents, reports, studies, maps, and resources related to the Protecting Our Waters CSO Control Program.

Project updates related to the ongoing construction in work areas 1 through 8 for the North Mercer Island/Enatai Sewer Upgrade Project.

Find a variety of project documents such as newsletters, fact sheets, graphics and environmental checklists.

Stay informed on the latest project news and updates and view previous project updates.

Find a variety of project documents such as environmental checklists and translated materials.

Stay informed on the latest project news and updates and view previous project updates.

Review fact sheets, FAQs, and environmental documents related to the Georgetown Wet Weather Treatment Station.

Find a variety of project documents such as environmental checklists and translated materials.

A set of documents and resources related to the Interbay sewer and odor control upgrade

Find a variety of project documents such as project updates, newsletters, and environmental checklists.

Find a variety of project documents such as environmental checklists and translated materials.

Stay informed on the latest project news and updates and view previous project updates.

What happens during a King County project? How is the public involved?

Information about capital project sites the Mitigation and Monitoring Program is actively monitoring, planning for, or have completed.

Find information about current and planned future Mouth of Duwamish Wet Weather Facilities projects.

Discover how King County is engaging the community around the Alki Standby Generator Project.

Discover how King County is engaging the community around the North Mercer Island/Enatai sewer upgrade.

Discover how King County is engaging the community in the West Duwamish Wet Weather Storage project.

Discover how King County is engaging the community around the Lake Hills and NW Lake Sammamish Sewer Upgrade.

Discover how King County is engaging the community around the Lakeland Hills Pump Station Replacement.

Discover how King County engaged the community around the Georgetown Wet Weather Treatment Station, from public art to community meetings and events.

Discover how King County is engaging the community around the Elliott West Wet Weather Treatment Station.

Discover how King County is engaging the community in these early planning stages in South Park.

Discover how King County is engaging the community around the M Street Trunk Rehabilitation Project.

Discover how King County is engaging the community around the Interbay Sewer and Odor Control Upgrade Project.

Discover how King County is engaging the community around Sammamish Plateau Diversion Project.

Discover how King County is engaging the community around the Coal Creek Sewer Upgrade Project.

Discover how King County is engaging the community around the ESI 8 Rehabilitation Project.

Learn how King County is working with the community to provide project information and identify potential impacts at Brightwater. 

Learn how King County is engaging the community around the Mouth of Duwamish Wet Weather Facilities.

Read past updates on rate and affordability studies.

King County periodically reviews its capacity charge rate structure to make sure the capacity charge program accurately reflects current demographics and housing trends.

This Wastewater Treatment Division report shares information about the services we provide, and explains the sewer rate and capacity charge to operate and maintain our regional treatment facilities.

This Wastewater Treatment Division report shares information about the services we provide, and explains the sewer rate and capacity charge to operate and maintain our regional treatment facilities.

The right water for the right use.

Ensuring quality of King County Recycled Water through research and testing.

The Regulatory Compliance and Land Acquisition Services unit handles the real property and permitting needs for all Wastewater Treatment Division (WTD) projects. These include managing existing property rights, acquiring new property rights, and obtaining land use, construction, and environmental permits.

Information about the agencies and organizations who work with the King County Industrial Waste Program.

Find out how we are leading the way in capturing and reusing energy to reduce our carbon footprint.

Brightwater Center features multipurpose meeting areas for community groups, conferences, weddings, and special events.

Find layout details of our multipurpose meeting areas at Brightwater Center and how to rent a room or space.

Find out how to contact King County about sewage spills and sewer odor problems.

Find 24-hour contact numbers and information to report odor problems coming from King County’s wastewater treatment plants or facilities.

Find reports, general information, and other resources about wastewater research and pilot studies.

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.

Check out our resource library for reports and general information about King County biosolids.

Find additional resources related to the Mitigation and Monitoring Program and environmental restoration.

Find I/I resources for local sewer agencies such as a side sewer maintenance mailer and best management practices toolkit and additional brochures, fact sheets, graphics, and maps.

When wastewater capital projects affect natural areas such as streams, wetlands, and other critical environments, the Mitigation and Monitoring (M/M) Program steps in to make sure that the areas are restored and that restoration continues to be successful.

The Rewards and Recognition Program recognizes industrial wastewater dischargers in King County that meet or exceed wastewater discharge permit requirements.

The Sammamish Plateau Diversion Project will build new wastewater infrastructure to serve the growing East Lake Sammamish area.

Information about King County’s Sediment Management Plan (SMP) to address historical sediment contamination near County combined sewer overflow (CSO) outfalls.

Information about how King County is addressing historical sediment contamination near County combined sewer overflow (CSO) outfalls, including the County’s Sediment Management Plan (SMP).

Learn about standards for construction site sedimentation tanks.

The Wastewater Treatment Division and the Solid Waste Division have established a process for appeals to any Determination of Non-significance (DNS) or Final Environmental Impact Statement (Final EIS) issued under the State Environmental Policy Act, or SEPA.

Information about the King County septage disposal facility, including how to get permitted, acceptable wastes, directions, and the septage disposal process.

Learn how King County is confronting climate impacts through heat energy reuse.

How is the sewer rate and capacity charge set?

Find information about the programs and services operated by the King County Wastewater Treatment Division to support the regional wastewater conveyance and treatment system.

How you experience construction activities depends on where you live, work, and play. To stay up to date on construction progress, you can sign up for area-specific emails.

Information about signature requirements for King County Industrial Waste Program forms.

King County is working on short-term and long-term solutions to reduce the risk of wastewater backups in South Park.

Studies have found a variety of chemicals including heavy metals, oil, industrial waste and sewage in the lower Duwamish river. The biggest chemicals of concern are polychlorinated biphenyls, or PCBs, which have been banned since the 1970s. PCBs are linked to cancer. Other toxins include arsenic and dioxins. PCBs, dioxins and arsenic are toxic to people and wildlife.

Learn how the Wastewater Treatment Division is providing the tools and expert guidance needed to prioritize sustainability best practices.

Find out how our regional wastewater treatment plants are implementing sustainability practices for our communities and the environment.

Brightwater Center was built with sustainability in mind, from the green building to the native plant landscape.

Planning and building new wastewater infrastructure is extremely complex. It can easily take a decade or more to go from identifying a project need to cutting the ribbon on a newly completed facility.

Helpful documents and resources for individuals, businesses, and facilities who discharge to the King County sewer system.

Find out how our Technology Assessment Program evaluates new and emerging technology to help us make informed decisions based on data and science.

The Thornton Creek Basin Sewer Study and Upgrade Project will ensure that the basin’s sewer pipe is able to carry wastewater flows to meet King County’s clean water goals into the future. 

Like all other urban waterways, the biggest ongoing source of pollution in the Duwamish today comes from stormwater runoff that carries chemicals from our cars, buildings, roads, businesses and yards. King County is working with the City of Seattle and the State Department of Ecology to find ways to control these sources of pollution.

Translated documents and content in 中文 (Chinese, simple), 正體字 (Chinese, traditional), and Español (Spanish).

Translated documents and content in Español (Spanish), Tiếng Việt (Vietnamese), 中文 (Chinese, simple), and 正體字 (Chinese, traditional).

Translated documents and content in عربي (Arabic), 中文 (Chinese, simple), 正體字 (Chinese, traditional), हिंदी (Hindi), русский (Russian), and Español (Spanish).

Translated documents and content in عربي (Arabic), Español (Spanish), Kajin M̧ajeļ (Marshallese), Tagalog, Українська (Ukrainian)

Translated documents and content in Español (Spanish)

Translated documents and content in 中文 (Chinese, simple), 正體字 (Chinese, traditional), and Español (Spanish).

Translated documents and content in Español  (Spanish) and ខ្មែរ (Khmer).

Translated documents and content in Español (Spanish), 中文  (Chinese, simple), and Русский  (Russian).

Translated documents and content in Español (Spanish), 中文 (Chinese, Simplified), 正體字 (Chinese, Traditional), 日本語 (Japanese), 한국어(Korean), and Русский (Russian).

Translated documents and content in Español (Spanish), Tiếng Việt  (Vietnamese), 한국어 (Korean), 中文  (Chinese, simple), 正體字 (Chinese, traditional), and Русский (Russian).

Translated documents and content in Español (Spanish), 中文  (Chinese, simple), and 正體字  (Chinese, traditional).

Translated documents and content in 中文  (Chinese, simple), 正體字  (Chinese, traditional), ;ខ្មែរ (Khmer), Español (Spanish) and Tiếng Việt (Vietnamese).

We have some of the largest wastewater treatment plants in the country. It takes a decade or more to build large wastewater projects, so it’s important we plan ahead.

Learn how wastewater can be recycled into reusable water, energy, and nutrients for plants and soil. Tours encourage visitors to think about responsible water use, the products they use, and how everyday choices can help protect our water.

Learn about the process we use to clean wastewater at Carnation.

Expand your career horizons and create a sustainable future in a paid internship with the King County Wastewater Treatment Division.

Information about King County’s project at the University Regulator Station (RS) Overflow to address historical sediment contamination near County combined sewer overflow (CSO) outfalls.

This page hosts information for consultants and contractors interested in doing business with King County Wastewater Treatment Division (WTD).

The Wastewater Treatment Division education team is providing programming at our sites and limited programming at schools. See below for upcoming public events and tours. If you have additional questions, please contact our staff.

Information about companies who violated King County wastewater rules.

Planning for and building the system needed to clean the wastewater generated by our region is technical and complex. Every day we face challenges managing population growth, keeping our system in good repair, and meeting existing and new regulations.

Come to our treatment plant sites to see unique artwork, enjoy nature, and learn about water. 

Find information about tours, educational and space rental opportunities, and trails and natural areas at Brightwater.

Learn more about the process to apply for a wastewater discharge permit.

Information and resources about biotechnology industrial waste authorization.

Information and resources about industrial waste authorization for breweries.

The King County Industrial Waste Program (KCIW) issues waste discharge permits to metal finishing facilities that discharge wastewater to the King County sewage system.

Information and resources about industrial waste authorization for wineries.

Learn more about King County wastewater discharge limits and regulations.

Download KCIW self-monitoring forms in either Microsoft Word or Acrobat PDF format.

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

King County Recycled Water is used for environmental projects and irrigation on farms and sports fields.

The Wastewater Treatment Division provides educational experiences about water for all ages, spaces for community events, and places to enjoy nature.

Waterworks Gardens is a public park located next to King County's South Plant in Renton, Washington.

Brightwater Center is a unique venue to host your wedding or special event that your guests will not forget.

King County’s plans to build a wet weather storage facility to hold stormwater and wastewater that currently overflows into the Duwamish River during large storms.

The Wheels to Water Program provides free water education field trip bus transportation to qualifying schools.

Learn about the King County Wastewater Treatment Division’s Workforce Development Program, including recruitment, mentorship, training, placement, and retention services for entry-level candidates who are building their skillset or are new to the clean water sector.

View and signup for WTD news releases and newsletter, check out clean water stories and get the news media contact for our division.