Buckle up for a big hike to King County sewer rates, with more increases expected

King County residents will see another significant increase in their sewer bills next year after county council members unanimously approved a 12.75% rate hike.

The increase will raise monthly sewer rates from about $63 per month to $71 per month in 2027 — an increase of about $8 per month for customers.

Council members acknowledged the financial burden the increase will place on residents.

“We are in violent agreement across this council and our partner jurisdictions that the wastewater treatment rates are going up at an alarming trajectory, and it is not sustainable,” Councilmember Claudia Balducci said during the King County Council meeting on Tuesday. Balducci represents the Eastside and is on the Regional Water Quality Committee (RWQC).

Councilmember Ron Dembowski said residents were surprised when they learned how much rates could increase.

“When I shared that with a group of constituents in Wedgwood at a neighborhood meeting, the jaws dropped, jaws dropped, and gasps were heard,” Dembowski said. “And that’s in the most progressive tax-friendly part of my district,” he said. Dembowski represents District 1, including Bothell, Kirkland, and North Seattle.

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Despite concerns about affordability, council members said the increase is necessary to repair and upgrade aging infrastructure, including $6.2 billion in capital projects, and to meet new regulations for wastewater treatment.

Several council members pointed to a recent visit to the South Treatment Plant in Renton as evidence of the need for continued investment.

“That reinforced for me the importance of these investments and the scale of the challenges ahead,” Councilmember Steffanie Fain said. Fain represents District 5, including Des Moines, Kent, and Renton.

Balducci also emphasized the importance of maintaining the county’s wastewater system.

“Not having a sustainable sewer system has really, really dire consequences for water quality and public health, and that’s our primary mission,” Balducci said.

The approved rate increase is expected to generate $676.2 million in revenue next year.

However, council members expressed concern about what comes next.

Under the Wastewater Treatment Division’s current proposed plan, double-digit rate increases would continue annually for the next five years. If that happens, monthly sewer rates could reach about $126 by 2032 — roughly double what customers pay today. Sewer rates would continue to increase at lower rates after that.

2026: $62.66

2027 (passed): $70.65

2028 (projected): $79.66

2029 (projected): $89.82

2030 (projected):$101.28

2031 (projected): $112.93

2032 (projected): $125.92

2033 (projected): $136.00

2034 (projected): $146.88

2035 (projected): $158.64

2036 (projected) $161.42

“I want to be clear, I don’t view rate increases of this magnitude as sustainable,” said Council Chair Sarah Perry. Perry represents District 3, including Duvall, Issaquah, and Woodinville.

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Council members said they are working with the Wastewater Treatment Division to find ways to slow future rate increases. Balducci said that includes examining regulations and looking at the science to figure out which investments are necessary to keep water healthy, but also to keep rates affordable.