King County targets 12.75% annual sewer-rate increases for 2028-29
King County Wastewater Treatment Division, Washington · Meeting date: November 4, 2026 · Published: November 6, 2026
King County Wastewater Treatment Division expects its forthcoming 2028-29 sewer-rate proposal to broadly follow the 12.75% annual increases forecast during the 2027 rate cycle. The division said it will have to identify reductions elsewhere in its work programme to hold to that ceiling as costs continue to rise.
Key points
- WTD expects to propose 12.75% annual sewer-rate increases in both 2028 and 2029, subject to executive-branch discussions and formal council action.
- The 2028-29 proposal would be the first two-year rate cycle under the division’s commitment to greater rate predictability.
- Although 2029 would still require formal council adoption in 2028 under existing contracts, WTD hopes to avoid a full second-year rate process.
- WTD reported $675 million in 2025 operating revenue; debt service represented 42% of annual expenses, while operations and maintenance accounted for about one-third.
Full report
King County Wastewater Treatment Division is preparing a two-year sewer-rate proposal for 2028 and 2029 that is expected to retain the 12.75% annual increases projected in the 2027 rate cycle.
The division’s director told the Regional Water Quality Committee that staff would treat the forecast as a ceiling, but said continuing cost pressures would require reductions in other parts of the work programme. Specific elements to be reduced had not yet been identified.
The process is starting earlier than previous rate cycles, before the division has closed its 2026 accounts. WTD said earlier and more detailed engagement with the Metropolitan Water Pollution Abatement Advisory Committee and the Regional Water Quality Committee should help inform the proposal.
The 2028-29 process is the first under WTD’s commitment to offer a two-year rate proposal to provide greater predictability. The 2029 rate would still need formal adoption by the King County Council in 2028 because of the division’s contractual requirements. However, WTD hopes a two-year proposal will allow it to avoid a second full rate-setting process in 2029, freeing capacity for work on the Regional Wastewater Services Plan.
The scale of existing financial commitments underpins the rate discussion. WTD reported annual operating revenue of about $675 million in 2025. Single-family customers supplied 45% of that revenue, while flow-based multifamily and commercial customers provided 36%. Capacity charges contributed 15% and industrial-waste charges 2%.
Debt service accounted for 42% of WTD’s annual expenses, with operations and maintenance representing about one-third. Cash-funded capital work accounted for a further 25%, primarily for repair and replacement of existing assets.
Alongside the near-term rate process, the committee reviewed longer-term alternatives to the regional rate structure. Options ranged from retaining the current uniform residential-customer-equivalent model to changing the conversion factor, charging all customers on a volumetric basis, billing local sewer agencies by total system flow, and adding infiltration-and-inflow or combined-sewer-overflow surcharges. WTD said further analysis of implementation requirements, cost shifts and trade-offs will be undertaken in 2027.
This summary was generated by AI based on the source document and may contain errors.
Source: Regional Water Quality Committee, King County Wastewater Treatment Division