Do I Need a Permit to Replace a Water Heater in Washington?

Water heater replacement permit requirements. Yes, even for like-for-like swaps. What inspectors check and how to pass.

Yes — even for a like-for-like replacement.

In Washington

WASHINGTON HAS ONE STATE BUILDING CODE IN FORCE EVERYWHERE, ADOPTED BY REFERENCE: "Except as otherwise provided in this chapter, there shall be in effect in all counties and cities the state building code which shall consist of the following model codes which are hereby adopted by reference:" IN ALL COUNTIES AND CITIES - the model codes named in that section are the code, without any act by your city. AND YOUR LOCAL GOVERNMENT MAY CHANGE IT, BUT ONLY IN ONE DIRECTION: "The governing bodies of counties and cities may amend the codes enumerated in RCW 19.27.031 as amended and adopted by the state building code council as they apply within their respective jurisdictions, but the amendments shall not result in a code that is less than the minimum performance standards and objectives contained in the state building code except as provided in subsection (2) of this section." NOT LESS THAN THE MINIMUM. So a local amendment may add to the state code and may not fall below it. That is the opposite arrangement from states that cap local rules at the model code, and it means a stricter local requirement in Washington is normal rather than suspect. FOR A HOUSE THERE IS A SECOND GATE, AND IT IS THE PART MOST READERS WOULD NEVER GUESS: "Except as provided in subsection (2) of this section, no amendment to a code enumerated in RCW 19.27.031 as amended and adopted by the state building code council that affects single-family or multifamily residential buildings shall be effective unless the amendment is approved by the building code council under RCW 19.27.074 (1)(b)." SHALL BE EFFECTIVE ONLY IF APPROVED BY THE BUILDING CODE COUNCIL. A local amendment touching single-family or multifamily residential buildings is not merely constrained - it does not take effect at all until a state council approves it. If you are told a local residential rule differs from the state code, that approval is the thing to ask about. ONE ADOPTION CARRIES AN EXCLUSION THAT DECIDES WHICH RULES APPLY TO PIPES: "The Uniform Plumbing Code and Uniform Plumbing Code Standards, published by the International Association of Plumbing and Mechanical Officials: PROVIDED, That any provisions of such code affecting sewers or fuel gas piping are not adopted;" THE UNIFORM PLUMBING CODE IS ADOPTED, BUT NOT ITS SEWER OR FUEL-GAS PIPING PROVISIONS. So a fuel-gas connection is not governed by the UPC here, and the applicable rule comes from elsewhere in the enumerated codes - worth confirming with the permitting office rather than assuming the plumbing code covers it. A WATER HEATER IS PLUMBING BEFORE IT IS ANYTHING ELSE, AND WASHINGTON IS A UNIFORM PLUMBING CODE STATE RATHER THAN AN INTERNATIONAL PLUMBING CODE ONE. That is the distinction to carry into a supply-house conversation: Richland adopts the "Uniform Plumbing Code with statewide amendments", Sammamish adopts it at SMC 16.05.140, and Shoreline lists it among its adopted codes - so fittings, venting and relief-valve details follow the UPC, and guidance written against the IPC is not the code here. THE SECOND THING IS THE ENERGY CODE: the Washington State Energy Code is separately adopted in each of those cities, and it is what governs efficiency and heat-pump provisions on a replacement - which is increasingly the part that decides what you are allowed to install rather than merely how to pipe it.

Why a Simple Swap Needs a Permit

Most jurisdictions require a permit for all water heater replacements, even when you're installing the same type and size. The permit ensures proper venting, gas connections, temperature/pressure relief valve discharge, and seismic strapping. Improper water heater installations are a leading cause of residential CO poisoning and water damage.

What Inspectors Check

The inspector will verify: gas line connections and drip leg (sediment trap), proper venting (metal B-vent for standard, PVC for high-efficiency), T&P relief valve discharging to within 6 inches of the floor or exterior, seismic strapping (two straps — upper and lower third), and adequate combustion air supply.

Tankless Conversion

Converting from a tank to tankless water heater often requires additional work: a larger gas line (tankless units draw more BTUs), PVC venting (most tankless units are high-efficiency), and potentially an electrical outlet for the unit. This may trigger both plumbing and gas permits.

DIY vs. Hiring a Plumber

Many jurisdictions allow homeowners to replace their own water heater in their primary residence — confirm with your city. You still must pull the permit and pass inspection. Most homeowners hire a licensed plumber because the permit and inspection process is simpler when the contractor handles it.

Yes, you need a $40-$60 permit. It's a quick same-day approval and one final inspection. Don't skip it — it protects you and your home.

Permit fees by city in Washington

Verified from each city’s published fee schedule. Where a city has no separate fee listed for this project, open the city page for the current requirements and amount.

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Permit fees by city in Washington
	Permit fee	Source
Bonney Lake	Set by city council resolutionVerified	Plumbing permit →
Des Moines	Set by the City Manager or designeeVerified	Plumbing permit →
Edmonds	Set by council resolution; not in codeVerified	Plumbing Permit →
Issaquah	8% of the building permit feeVerified	Plumbing Permit →
Kenmore	Set by adopted fee scheduleVerified	Plumbing permit →
Lake Stevens	Set by city council resolutionVerified	Plumbing Permit →
Longview	Set in the master fee scheduleVerified	Plumbing Permit →
Lynnwood	Set by city council fee ordinanceVerified	Plumbing Permit →
Maple Valley	Set by Development Fee ScheduleVerified	Plumbing permit →
Mercer Island	Set by city council resolutionVerified	Plumbing permit →
Moses Lake	Set by city council resolutionVerified	Plumbing permit →
Mountlake Terrace	Set by annually adopted fee scheduleVerified	Plumbing permit →
Oak Harbor	Not stated in this guide - see notesVerified	Plumbing permit →
Pullman	Set by city council resolutionVerified	Plumbing permit →
Puyallup	Set by city manager executive orderVerified	Plumbing Permit →
Sammamish	See city page for the current Residential Building Permit fee	Residential Building Permit →
SeaTac	Set by City of SeaTac Fee ScheduleVerified	Plumbing permit →
Tumwater	Set by city council resolutionVerified	Plumbing permit →
University Place	Set by city council fee resolutionVerified	Plumbing Permit →
Walla Walla	$23.00 issuance plus per-fixture feesVerified	Plumbing permit →
Wenatchee	Not published in code; ask the cityVerified	Plumbing Permit →

See the national overview for this permit →