Summary
A new sewer rate proposal for 2027 would provide King County’s Wastewater Treatment Division the resources it needs to protect water quality and public health while outlining specific actions to achieve long-term affordability.
News
Today, a new proposal for the 2027 sewer rate was transmitted to the King County Council that would provide the regional wastewater treatment system with the resources it needs to protect water quality and public health while outlining new actions to achieve long-term affordability.
The proposed 12.75% increase would make it possible for King County’s Wastewater Treatment Division to comply with state and federal regulations, maintain and modernize aging infrastructure, and increase capacity to serve a growing population.
“The proposed sewer rate will make sure our frontline professionals have the resources they need to protect the water that sustains life in our region,” said King County Executive Girmay Zahilay. “We have an obligation to the people we serve to be just as effective at financial stewardship as we are at environmental stewardship. That’s why I have directed our Wastewater Treatment Division to work with partners to create a sustainable future that achieves goals for affordability while also protecting human and environmental health.”
King County’s Wastewater Treatment Division – which serves nearly 2 million people – provides wholesale wastewater treatment services to a combined 33 cities and local sewer utilities in King, Snohomish, and Pierce counties, along with the Muckleshoot Indian Tribe. Frontline employees treat an estimated 178 million gallons of sewage each day, maintaining and operating three regional wastewater treatment stations, two community-scale plants, dozens of pump and regulator stations, and nearly 400 miles of major sewer conveyance lines.
It will cost the Wastewater Treatment Division an estimated $14 billion over the next decade to meet deadlines for state and federal regulations, modernize infrastructure that has been operating nearly nonstop for decades, and increase the treatment system’s capacity to serve more homes and businesses.
If the proposed sewer rate is approved by the County Council, the average ratepayer would see an increase of about $8 per month for the County wastewater treatment portion on their utility bill.
“This proposal demonstrates the County’s commitment to protecting the water quality of King County while directing the Wastewater Treatment Division to make sure we’re on a financial path that is sustainable,” said John Taylor, Director of the Department of Natural Resources and Parks. “I’m looking forward to working with our partners to achieve a shared vision that achieves both affordability and reliability.”
Multiple actions to promote long-range affordability
Executive Zahilay directed the Wastewater Treatment Division to take multiple actions to promote affordability, including:
- Engage with local, state, and federal partners – including cities, sewer districts, Tribes, and regulatory agencies – to create a path toward a financially sustainable future that also protects human and environmental health.
- Work with the Metropolitan Water Pollution Abatement Advisory Committee, known as MWPAAC, and other advisory bodies to further improve rate predictability and transparency in project prioritization.
- Incorporate affordability into the planning process for its Regional Wastewater Services Plan, including developing metrics and evaluating innovative rate relief approaches for low-income customers.
- Enhance efforts to contain capital and operational costs and continue cooperation with an independent third-party review for its capital program.
- Continue to reduce ratepayer costs by successfully competing for low-interest loans and loan flexibility offered by state and federal agencies.
A 6.55% increase was also transmitted to the capacity charge, which is paid by new users of the sewer system to help with the cost of capacity improvements.
“We recognize that higher sewer rates add to the already high cost of living in the Puget Sound region, and that the greatest impacts are felt by households making lower incomes,” said Kamuron Gurol, Director of the King County Wastewater Treatment Division. “As stewards of public dollars, we are committed to getting the best value possible for each ratepayer dollar and implementing a rate-setting process that is transparent, fact-informed and thorough. We’re leaving no stone unturned to keep rates as affordable as possible for all the communities, families and businesses we serve.”
What’s driving the increase? Regulations, aging infrastructure, growing population
Past rate increases have been more gradual and tied to smaller drivers, such as rising costs for electricity and chemicals. This year, the Wastewater Treatment Division is forecasting the start of a series of double-digit increases, driven largely by state and federal regulatory requirements – on top of investments needed to ensure the treatment system remains safe and reliable – with deadlines stacking up in a short period of time.
About half of the projected costs over the next decade – an estimated $7 billion – are needed to comply with state and federal regulations.
The Wastewater Treatment Division is required to reduce the frequency of combined sewer overflows. These safety relief valves were installed in the 20th century with Seattle’s original system to prevent sewage from backing up into homes and businesses when heavy rainfall fills pipes that carry both sewage and stormwater. The agency has substantially decreased the number of overflows that occur each year, though a federal consent decree King County signed with the state Department of Ecology and the U.S. Environmental Protection Agency requires a further reduction in overflows by 2037.
The proposed rate would also help the agency meet conditions of a National Pollutant Discharge Elimination System permit for West Point Treatment Plant in Seattle and cleanup efforts at the Lower Duwamish Waterway Superfund site. King County, along with the City of Seattle and Boeing, have successfully negotiated with dozens of other responsible parties to pay for fair-share costs for removing historic pollution.
Much of the regional wastewater system has been operating reliably each day since it was built in the 1960s, and some pieces of that infrastructure are nearing the end of their service life.
Frontline employees at the Wastewater Treatment Division are highly effective at maintaining and operating aging equipment, but daily wear and tear – combined with the corrosive nature of wastewater – has pushed some equipment to the point where replacement parts are no longer available.
As the Central Puget Sound region’s population continues to grow, the number of homes and businesses that require sewer service keeps rising as well. That will require additional pipeline capacity, more pump station capacity, and a larger workforce to effectively maintain and operate the regional treatment system.
A current example is a major sewer upgrade in Bellevue that is the first of its kind to earn Salmon-Safe certification, modernizing critical infrastructure to serve a growing population while improving habitat for fish and wildlife and increasing access to nature for all abilities.
Reinforcing King County’s reputation as a trusted financial steward
The Wastewater Treatment Division has earned a reputation as a trusted financial steward over the decades, maintaining high credit ratings that reduce interest fees charged to ratepayers.
The agency has secured low-interest loans from federal and state sources such as the Washington State Revolving Fund, Washington Public Works Trust Fund, and the federal Water Infrastructure Finance and Innovation Act. Capitalizing on the state’s revolving fund alone has saved ratepayers $162 million over the past decade.
The agency has also reduced costs by bringing more functions in-house, decreasing reliance on contract services. For example, the agency’s conveyance inspection team performs regular inspection surveys and maintenance for county-owned pipes each year. In August 2025, King County added a new sewer cleaning truck, helping the team complete nearly 25 miles of pipe inspection and clean more than 100,000 feet of sewer lines annually.
The Wastewater Treatment Division has completed multiple improvement projects in recent years that have made the regional system safer, more reliable, and more energy efficient. That includes the new onsite battery power crews installed at West Point Treatment Plant that has proven be effective at keeping critical pumps operating during power disruptions.
The Wastewater Treatment Division is one of four divisions at the King County Department of Natural Resources and Parks.
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Quotes
“The proposed sewer rate will make sure our frontline professionals have the resources they need to protect the water that sustains life in our region. We have an obligation to the people we serve to be just as effective at financial stewardship as we are at environmental stewardship. That’s why I have directed our Wastewater Treatment Division to work with partners to create a sustainable future that achieves goals for affordability while also protecting human and environmental health.”
Girmay Zahilay
King County Executive
“This proposal demonstrates the County’s commitment to protecting the water quality of King County while directing the Wastewater Treatment Division to make sure we’re on a financial path that is sustainable. I’m looking forward to working with our partners to achieve a shared vision that achieves both affordability and reliability.”
John Taylor
Director, King County Department of Natural Resources and Parks
“We recognize that higher sewer rates add to the already high cost of living in the Puget Sound region, and that the greatest impacts are felt by households making lower incomes. As stewards of public dollars, we are committed to getting the best value possible for each ratepayer dollar and implementing a rate-setting process that is transparent, fact-informed and thorough. We’re leaving no stone unturned to keep rates as affordable as possible for all the communities, families and businesses we serve.”
Kamuron Gurol
Director, King County Wastewater Treatment Division
Contact
Akiko Oda, Wastewater Treatment Division