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Sewer extensions

A description of sewer extension projects and the roles and responsibilities of the Local Public Agency team and the local agency.


Sewer extensions are new public sewers connecting to existing local sewers owned by the Local Agency that connect to the King County sewer system downstream. They are essentially extensions to the Local Agency sewer. Examples of sewer extensions include, but are not limited to, local public sewers for new single-family houses, apartments, businesses, or schools.

Sewer Extension Requirements

Proposals for new sewer extensions need to be submitted to the Local Agency first to go through their approval process. The local agency then submits the final plans to the LPA team for its review and approval.

Our team’s role

The LPA teams reviews the final plans and provides approval of the sewer extension. Approval is in the form of a letter addressed to the Local Agency.


Graphic shows examples of sewer extensions that are connections for new single-family houses, apartments, businesses, shopping centers, restaurants, or schools