Do I need a plumbing permit in King County?
For most real plumbing work, yes, and the permit comes from an office most people don't expect. Public Health - Seattle & King County issues plumbing and gas piping permits in Seattle and unincorporated King County, not the construction department that handles building permits. Their rule is broad: whenever you install, relocate, or change a plumbing or gas piping system, the code requires a permit.
What that covers in practice
- Covered: new or moved fixtures, repipes, water heater replacements, gas line work, sewer line work, adding a bathroom or hose bib
- Usually not covered: swapping a faucet or toilet in place, clearing a drain, repairing a valve, since maintenance doesn't change the system
The line is whether the work changes the plumbing system, not how big the job feels. Replacing a water heater is a permit job in this jurisdiction even though it's a same-day swap.
Who pulls it
The plumber does. Licensed plumbing contractors pull their own permits through the Public Health Permit Center, and the permit shows up on the property's record. Washington also allows homeowners to pull a permit for work they do themselves in their own home, which is the legal DIY route.
The reader-facing check: when the job is permit-sized, ask whether the quote includes the permit and the inspection. A company that hesitates on that question is telling you something about how the work gets documented.
Why it matters to you
- Inspection: a permitted job gets looked at by someone whose job is catching mistakes before the wall closes
- Resale: unpermitted work surfaces on inspection during a sale, and buyers' inspectors ask for permit history on water heaters, repipes, and additions
- Insurance: a claim tied to unpermitted work gives the adjuster a reason to push back
If you're not sure whether your job crosses the line, say what the work is in the request. The plumber who calls can tell you whether a permit applies before you get a quote.
