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Sewage Treatment Capacity Charge

Growth paying for growth

King County
Wastewater Treatment Division
Capacity Charge Program
201 S. Jackson,
M.S. KSC-NR-0502
Seattle, WA 98104

Phone: 206-296-1450
Fax: 206-263-6073
E-mail: CapChargeEscrow

The capacity charge helps King County cover the cost of sewer improvement and expansion projects needed to serve new growth.

Frequently asked questions - King County Capacity Charge Program

See also Frequently Asked Questions about the sewer rate and capacity charge on the Wastewater Treatment Division site, including "I live in Snohomish (or Pierce) County–why am I paying for King County's wastewater treatment service?"

What is the capacity charge?
The sewage treatment capacity charge is a charge in addition to sewer service billed to those customers who connected to the sanitary sewage system on or after Feb. 1, 1990.
Why do we have a capacity charge?
To protect public health and the environment, King County’s wastewater treatment system must keep pace with growth in our region. That means building more pipes, pump stations, and treatment plants.

The capacity charge distributes the costs for this expanding infrastructure to customers with the newest sewer connections. In other words, the capacity charge helps make sure that “growth pays for growth.”

Who must pay?
All homeowners and building owners in King County’s service area whose home or building was newly connected to the King County sewer system on or after Feb. 1, 1990 pay the capacity charge. King County provides sewage treatment services to most cities and sewer agencies in King County, areas of south Snohomish County, and a small part of Pierce County.
How much is it?

The 2015 capacity charge is $57.00 per residential customer equivalent (RCE) per month. To calculate a residential property's monthly rate, use the following formulas:

  • A single-family house = 1 RCE x $57.00 = $57.00 per month.
  • 2-4 units in a multi-family building = 0.8 RCEs per unit.
    For example: 2 units x 0.8 = 1.6 RCEs x $57.00 = $91.20 per month.
  • 5 or more units = 0.64 RCEs per unit.
    For example: 6 units x 0.64 = 3.84 RCEs x $57.00 = $218.88 per month.

For other non-residential property, the capacity charge is determined by plumbing fixtures or wastewater flow projections converted to RCEs.

How is it billed?
King County sends capacity charge bills to property owners about three months after connection to the sewer system. King County will then send a bill every three months for 15 years, or until the balance of the property’s account is paid.

You can remit payment by U.S. mail or by using the online payment system.

What are my payment options?

At any time during the 15-year duration of the charge, you may pay the remaining balance in one lump sum at a discount. If you include the payoff amount in your mortgage, it might provide a tax advantage. However if you are likely to sell your property within a few years of buying it, you may not want to prepay future charges because the remaining payments could be passed along to the next owner.

You can now pay your bill online.

What do I do when I sell my home and the 15-year billing period is not over?
You may want to consult with your real estate agent regarding disclosure to prospective buyers and escrow agents handling your transaction. (RCW 64.06.020 and RCW 60.80).
What is the money used for?
King County’s wastewater treatment system protects public health and the environment by treating wastewater before recycling it or releasing it into Puget Sound. Increasing demand on the regional sewage treatment system has meant building new treatment facilities and expanding capacity of the current system. Examples of this needed expansion include the new Brightwater Treatment Plant in Woodinville, expansion of the Sunset and Heathfield Pump Stations in Bellevue, and the Southwest Interceptor project in the Kent-Auburn area. View more projects under construction.
Will the rate go up?
The King County Council reviews and establishes the amount of the capacity charge annually. Increases apply to new connections only—they are not retroactively applied to existing accounts.
Will I also get a bill for sewer service?
Yes. You will receive a sewer service bill from your local sewage service provider. The bill from your local agency will include both local charges for sewage collection and regional charges from King County for sewage treatment and disposal. The bill from King County will be for the capacity charge only.
Why is the rate of my capacity charge bill different from my neighbor's, yet our houses were built about the same time?
The capacity charge rate is based on the date of the property’s final side sewer inspection. Homes built about the same time may have been inspected in different years. Rate increases do not apply to existing connections. Each property is billed at the prevailing rate at the time the inspection took place.
Why didn't the developer pay this charge?
By law the capacity charge is a monthly charge triggered by connection to the sewer system, not an upfront cost of development. The capacity charge is the responsibility of the current property owner.
What is the legal basis for this charge?
The Revised Code of Washington, Chapter 35.58.570, and King County Code No. 28.84.050 are the legal basis for the capacity charge. Under these laws, a lien may be filed against a property that has delinquent or unpaid charges.
Who can I contact about my bill?

For questions about your capacity charge bill:

King County Capacity Charge Program
201 S. Jackson, M.S. KSC-NR-0502
Seattle, WA 98104
Phone: 206-296-1450
Fax: 206-263-6073

For questions about your sewer service bill, contact your local sewage service provider.


  • King County offers the option to pay off the capacity charge at a discount when all outstanding invoices are paid in full. Effective January 1, 2014, the discount rate has been revised to more closely reflect economic trends.

Related information

Revised Code of Washington (RCW)

  • RCW 64.06.020, Improved residential real property — Seller's duty — Format of disclosure statement — Minimum information
  • Chapter 60.80 RCW, Lien for unrecorded utility charges