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Plumbing and gas piping applications and permits

Learn how to submit a plumbing or gas piping plan review application or get a homeowner's permit.

Permit applications

Use the Online Services Portal to purchase plumbing, backflow assemblies, gas piping, medical gas permits, and submit Design Documents for Plan Review.

Plan review information

A plumbing plan review must be completed by Public Health - Seattle & King County (PHSKC) for certain occupancies.

For questions about the plumbing plan review process, please email

Getting a homeowner's plumbing permit

Plumbing can be difficult. Public Health - Seattle & King County recommends you hire a professional plumber. If you choose to do your own plumbing, please adhere closely to the following instructions.

How to get a homeowner's plumbing permit

When a permit is required

Whenever you are going to install, relocate, or change a plumbing or gas piping system, Seattle and King County codes require that you obtain a permit. PHSKC has jurisdiction in Seattle and unincorporated King County.

The permit issued to a homeowner is an authorization for the homeowner to do the plumbing. (See RCW 18.106.150) If you are being authorized by the property owner to apply for the plumbing permit, your signature on the permit application signifies that you have such authorization from the owner of the property. If a professional plumber is contracted with, they must be a registered contractor per Chapter 18.27 RCW.

Permit jurisdictions

PHSKC issues plumbing and gas piping permits, and performs inspections, in the following jurisdictions:

  • Seattle
  • Unincorporated King County
  • Beaux Arts
  • Clyde Hill

If the property is in another King County city, you will need to get your plumbing and gas piping permits from that city's building department.

If you are uncertain about the jurisdiction, please use the King County Parcel Viewer to check. Use care when entering the parcel number and property address for your permit. If our inspectors are sent to the wrong site due to your error, you may be charged a $25 change-of-address fee.

For permits issued online, you will need to wait for an hour before you can call to request an inspection.

Renewal of an existing permit or the addition of fixtures/outlets to an existing permit cannot be done online but you can do it over the phone. Call 206-263-9566 and have your SR# and a credit card available.


Effective March 15, 2024, projects in unincorporated King County will be required to be designed using the 2021 Washington State construction codes unless project building permit is vested in a previous code cycle.

Adoption of the 2021 Seattle construction codes has been postponed to no sooner than July 1, 2024. Until the 2021 codes are officially adopted, PHSKC will accept applications for projects located within the City of Seattle using either the 2018 or 2021 suite of codes.

Check for ongoing updates:

City of Seattle code adoption page