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In King County’s wastewater service area, owners of buildings with new sewer connections, additions or changes of use pay their share of the cost of sewer infrastructure through a capacity charge. Two studies began in 2017 to look at the affordability and rate design of the capacity charge.

December 2019 update

For the latest update on the capacity charge rate design study, read our December 2019 newsletter .

Capacity charge rate design review

The Rate Design Review looks at how the capacity charge is allocated to different groups of customers. Since the capacity charge program began in 1990, King County has experienced significant growth and change. Emerging trends include micro-housing, small efficiency dwelling units, accessory dwelling units, detached accessory dwelling units, group housing, adult care homes and the installation of low-flow plumbing fixtures. It is time to evaluate the best approach for allocating the capacity charge in light of the wastewater demand for today’s building types.

This study focuses on a technical question – how best to define the basis of the capacity charge. Our goal is for the charge to reflect the amount of wastewater that each type of building is likely to send to the King County wastewater system. The charge must also be administratively workable for both developers and development review staff. And it must be based on information that can be known at the time of development—before a particular building has a track record of water consumption.

See fact sheet for more information.

Low income customer assistance

King County Wastewater Treatment Division recently implemented new affordability options for capacity charge customers based on the findings of a Low-Income Customer Affordability Study . The new assistance programs approved by the King County Council and signed by the Executive took effect June 29, 2019. Assistance aimed at customers experiencing financial hardship include:

  • Payment deferral for low-income seniors and disabled individuals: Customers who enroll in the State and County property tax exemption program for seniors and disabled individuals may be eligible to wait until they sell their property to pay the capacity charge.  King County will place a property lien for the balance owed and collect the funds when the property is sold. The interest rate is reduced to 5 percent annually and late fees are waived, however a recording fee will apply.
  • Improved payment plan options: Payment plans for the capacity charge can be more flexible. They allow customers to catch up on late bills through smaller, more frequent payment plans. 
  • Connecting customers to resources: Staff can refer customers to Washington 211, which provides referrals to a variety of health and human services.
  • Affordability for new low income housing: More types of eligible low-income housing can qualify for a discounted capacity charge. Eligible new units will be assigned 0.32 residential customer equivalents, which in most cases represents a 50 percent discount. See this table for details on qualifications by housing type.

Next steps

The Low-Income Customer Affordability Study is completed and new assistance programs approved by the King County Council and signed by the Executive took effect June 29, 2019. The Rate Design Review recently finished and King County is seeking feedback from the public on the recommended changes to the capacity charge rate structure.

Contact Us

Phone: 206-296-1450

Fax: 206-263-6073