On a septic system?

You will need to contact Public Health-Seattle & King County Onsite Sewage Systems (OSS) to find if OSS review or a permit is required for your project.

Verification from OSS may be required with your building permit application.

Examples include: Additions to dwellings, detached buildings, and remodels that increase the number of bedrooms.

Visit OSS webpage: https://kingcounty.gov/depts/health/environmental-health/piping/onsite-sewage-systems.aspx.

Navigate to “Septic expert office hours” contact information and “Resources for Residents on Septic” – “Homeowners on a septic system”


Show All Answers

1. When is a building permit required?
2. Why should I get a permit?
3. Where do I submit a permit?
4. How do I schedule an inspection?
5. Tips for Selecting an Architect, Engineer, Design Professional
6. On a septic system?
7. A Guide To Landlord Tenant Issues