Apply for King County Public Health plumbing permit

The agency people miss

Plumbing permits inside Seattle are issued by King County Public Health, not SDCI. It trips up homeowners who assume all city permits are SDCI. Your licensed plumber files it.

What's covered

The plumbing permit covers all plumbing inside the new cottage: water supply, drain-waste-vent (DWV), fixture connections, water heater (HPWH is a heat pump, but the plumbing-side connection is here), gas piping (if any).

The connection from the cottage's DWV to the main and from the main to the city sewer is covered by the side-sewer permit (step 3.3) — different agency.

Cost

Varies by fixture count and connection complexity. Budget a few hundred to low thousands.

Verification

• Plumber: L&I plumber license lookup.
• Permit status: King County Public Health Permit Center.

Sequencing

File in parallel with the other three permits (3.1, 3.2, 3.3). The plumber needs the schematic plumbing layout to apply, so this happens once Phase 2 design is essentially complete.