Plumbing Permit Requirements in Seattle, WA
Seattle splits plumbing oversight in a way that surprises out-of-town crews. Here is who issues what, and which side-permits attach to a sewer or water service job.
Know which agency owns your scope
Plumbing permitting in Seattle is not a single counter. Interior plumbing, side sewers, and water service work can involve SDCI, Public Health — Seattle & King County, and Seattle Public Utilities depending on what you are touching. Identify the issuing agency before you assemble the packet; filing with the wrong one costs a full cycle.
Side sewer work in particular has its own permit path and its own contractor registration expectations. If your job crosses the property line into the right-of-way, assume additional review and a street-use component.
Registration and licensing come first
Washington requires state plumber certification for the people doing the work and a registered contractor for the business filing the permit. Seattle checks both. Expired registration is a hard stop, and it is checked at intake rather than at inspection, which is the one piece of good news here.
Fees: confirm before you quote
Seattle's plumbing and side sewer fees vary by agency and scope and are revised on an annual cycle, so we do not publish a formula here without a current primary source. Confirm with the issuing agency for your specific scope.
How to read this page
This is a research summary for licensed contractors. It is not legal advice, and PermitCrab is not a filing service. We read the code, compare it against what actually happens at the counter, and publish what a contractor pulling this permit for the first time would want to know before they drive over.
Where we do not have a primary source we can cite, we say so instead of guessing. Fee schedules and submittal rules change without much warning, so treat any unverified section as a phone call you still owe the department.