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Public Health - Seattle & King County

How to install, repair or replace your septic system

Permits

All septic systems require a permit for new installations, repairs and replacements, house or building remodels or expansions, subdivisions, boundary line adjustments and rezones. Click below for more information about each permit:

Wastewater applications and forms (PDF)
NOTE: A septic system is also referred to as an "on-site sewage system" or OSS in official documents, forms and applications.

Wastewater applications:

Wastewater forms:

Miscellaneous forms:

Wastewater manuals for homeowners
Codes from local and state Boards of Health and WAC
NOTE: A septic system is also referred to as an "on-site sewage system" or OSS in official documents, forms and applications.