How much does it cost to replace a water heater?

Angi puts the 2026 national average at $1,348, from 30,979 projects, with most people paying $882 to $1,826. Tankless heaters, a change of fuel, new venting or gas line work cost more.

Do I need a permit to replace a water heater in Seattle or King County?

Yes. Public Health – Seattle & King County requires a plumbing permit for every replacement water heater from July 1, 2026, not only for changes of type. A permit not taken out at the start costs an administrative fee, and from January 1, 2027 double the standard fee.

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What does it cost to replace a water heater?

Angi puts the 2026 national average at $1,348, from 30,979 projects; most people pay $882 to $1,826. Tankless heaters, a change of fuel, and new venting or gas line work cost more. In Seattle and unincorporated King County, every replacement now needs a plumbing permit.

What makes it cost more

1Tankless or heat pump instead of a tank. More for the unit, and often more work to fit it.

2Changing fuel. Gas to electric needs a circuit; electric to gas needs a gas line and venting.

3Moving it, or a hard place to reach. An attic or a tight closet takes longer than a garage.

4Bringing it up to code. The installer may need to add parts the old one went without, and the permit itself.

Ask for a written estimate that says what's included: the heater, haul-away of the old one, parts and the permit.

Permits in Washington

Seattle and unincorporated King County: a permit for every replacement, from July 1, 2026

Public Health – Seattle & King County now requires a plumbing permit for all replacement water heaters, not only changes of type. One not taken out at the start costs an administrative fee; from January 1, 2027, double the standard fee.

Electrical work: if the job changes the wiring, such as a new circuit or switching from gas to electric, it needs an electrical permit from L&I, or from your city if it does its own. Anywhere else in Washington: ask your city or county permit office. A registered plumber pulls the permit as part of the job.

Is yours due?

Most tank heaters last 8 to 12 years. Photograph the label to see how old yours is, or read the serial number for Bradford White, A.O. Smith and State or Rheem and Ruud.

Get one registered pro to call me

Sources

Angi: how much does water heater replacement cost? (2026 data)

Public Health – Seattle & King County: preparing for replacement water heater permitting · Permits for all replacement water heaters from July 1, 2026; an administrative fee for a late permit, double the fee from January 1, 2027.

Public Health – Seattle & King County: plumbing and gas piping permits · Public Health has jurisdiction in Seattle and unincorporated King County.

L&I: electrical permits, fees and inspections