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Disposal costs

Information on the rates and fees to dispose of septage at the septage disposal facility at South Treatment Plant.

The rates and fees to dispose of septage at the septage treatment facility at South Treatment Plant are as follows:

Disposal Rate
(January 1 through December 31, 2026)		 $0.1745 per gallon*
We weigh each load and charge $0.0209232 per pound discharged. This covers domestic septic tank waste and portable toilet waste, up to 2% solids.

Note: the disposal rate includes $0.01 per gallon on-going surcharge to provide funds for Public Health-Seattle and King County to respond to failing on-site sewage systems (OSS), provide technical support to property owners wit  h OSS, identify and repair prioritized OSS failures, continue “what not to flush” education and outreach, and improve industry reporting.
Fees Annual fee: $200/year/truck
Initial setup fee: $50/truck