Water heater permit checklist — King County, Washington
Assembled from King County’s own published permit rules. Every line below is quoted from a city document and linked to it. Nothing here is generated, estimated, or inferred from another jurisdiction.
Do you need a permit?
King County requires a permit for a water heater.
Another jurisdictional split: plumbing and gas piping in unincorporated King County is permitted by Public Health - Seattle & King County (PHSKC), not by the Permitting Division. PHSKC's jurisdiction covers Seattle, Clyde Hill and unincorporated King County; every other city in the county issues its own plumbing permits. PHSKC states that '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,' and as of July 1, 2026 replacement water heaters specifically require a permit — typically issued over the counter. There is no de minimis exemption for a like-for-like water heater swap, which is the opposite of Maricopa County's approach. Gas water heaters additionally require a gas piping permit if the gas line is altered. Homes on septic should note that septic work is a separate PHSKC on-site sewage permit.
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Sources
- water heater — permit rules ↗verified August 2026
Other permits King County publishes rules for
Listed because the city publishes a separate rule for each type — not because this project necessarily triggers one. Whether it does depends on your scope of work.
- Deck permit checklist
- Fence permit checklist
- Shed permit checklist
- Re-roof permit checklist
- Retaining wall permit checklist
- Electrical work permit checklist
- General building work permit checklist
BuildSpec is a reference, not the authority having jurisdiction. Confirm requirements with King County before you build.