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Public Health - Seattle & King County

Permit information for new septic construction

Design phase

An approved site application design is required when a new septic system* is constructed (an approved design is not an installation permit). Construction must not begin until the installation permit is posted on the site/property.

All designs are to be submitted by the designer to Eastgate Environmental Health with the appropriate fee and design checklist.

*A septic system is also referred to as an "on-site sewage system" in official documents, forms and applications.

Forms used by Septic System professional:

Permit issuance

Designer responsibility:

After the design submittal has been approved and construction begins on the building, a Pre-installation Inspection Report and Operation and Maintenance Contract/Agreement (for sand filters and ATU's only) must be submitted by the designer to the Eastgate Environmental Health office. The designer is responsible for forwarding a copy to the Master Installer.

Master Installer responsibility:

A copy of the building permit (first page), Application for On-site Sewage System Installation/Repair Permit, and a copy of the Designer's OSS Pre-Installation Inspection Report is submitted by the Master Installer to the Eastgate Environmental Health office.

After the forms are evaluated by the Health Inspector, a permit is issued or a request for additional information by the Health Inspector.

Forms used by OSS professional:

  • OSS Pre-installation Installation Check List (for stub-out release)
  • Designer's OSS Pre-installation Inspection Report (for stub-out release) (not available online)
Install phase

The Master Installer installs the septic system and contacts the Designer for pressure tests (if applicable) and as-built inspection. Designer signs permit and notifies Public Health that the system is ready for health inspection. The Health Inspector inspects the installed system and signs permit, if approved. Master Installer backfills the system and notifies Designer through the Installer's Backfill Notification Request for Final Inspection.

As-built phase

The Designer makes a final cover inspection and prepares the as-built documents for the system. Designer submits As-built Certification of Completion, As-built Checklist, Notice of On-site Sewage System Operation and Maintenance Requirements document, and other applicable documents to the Eastgate Environmental Health office. Upon Health Inspector approval or disapproval, the Health Inspector will return a signed copy of the As-built Certification of Completion form to the Designer and OSS owner.

Forms used by Septic System professional: