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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.

July 2020

The King County Council is expected to consider proposed changes to the capacity charge rate structure in the coming months. To follow the legislative process, visit the King Council Council’s webpage for Ordinance 2020-0102 establishing policy of average persons per household and Ordinance 2020-0101 for implementation and revising customer classifications.

For the latest update on the capacity charge rate study, read our Summer 2020 Update .

Capacity charge rate study

King County Wastewater Treatment Division has proposed changes to the capacity charge rate structure that elected officials will vote on later this year. 

The proposed package of legislation would establish the basis of the capacity charge as average persons per household. Using persons per household, based on data from the U.S. Census Bureau, would reflect the approximate amount of wastewater each type of unit sends to the sewer. For single family homes, the proposed legislation means that small homes would pay less for the capacity charge and large homes would pay more based on the average persons per household for small, medium and large homes. Residential Customer Equivalent (RCE) assigned to single family homes will be based on size: small (<1,500 sq. ft. = 0.81 RCE), medium (1,500 – 2,999 sq. ft. = 1 RCE), and large (>3,000 sq. ft. = 1.16 RCE).

The proposal does not recommend changes to the categories for other types of residential units or commercial structures. However, using persons per household data would result in small changes to RCEs assigned to these other categories. The proposal would also confirm previous changes for accessory dwelling units like backyard cottages and basement apartments and set a 0.59 RCE.

The proposal is designed to be revenue-neutral so that it does not increase the overall total amount that King County collects through the capacity charge. 

The proposed changes to the capacity charge rate structure would require a change to King County Code. If approved by the King County Council, the capacity charge rate structure changes is anticipated to take effect on January 1, 2021, along with the previously approved 3 percent capacity charge rate increase for 2021. 

To follow the legislative process, visit the King Council Council’s webpage for Ordinance 2020-0102 establishing policy of average persons per household and Ordinance 2020-0101 for implementation and revising customer classifications. 

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.

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Phone: 206-296-1450

Fax: 206-263-6073