Short definition
Water heater replacement is the most common large plumbing job in WA homes. State code requires a permit, two seismic straps, a properly piped TPR discharge, a drain pan, and (in most modern homes) an expansion tank. Costs in 2026 run roughly $1,400–$3,200 for like-for-like tank, $4,500–$7,500 for tankless, and $4,500–$8,500 for a heat pump water heater — before utility rebates and federal tax credits that make HPWH net-cheaper for many homeowners.
What it is
Water heater replacement is end-of-life swap of the appliance that supplies hot water to the building. The trigger is usually one of three things:
- Leak. Tank corroded through; replacement is immediate.
- Sediment failure. Rumbling, low recovery, hot water doesn’t last; tank’s full of mineral scale.
- Age. 10–12 years for a standard tank, 15–20 for tankless or heat pump water heater. Proactive replacement before the leak avoids water damage.
A code-correct replacement in WA includes more than just swapping the tank. The inspection checklist:
- Seismic strapping at the upper third and lower third of the tank, anchored to wall framing.
- TPR (temperature-pressure relief) valve with a discharge tube to within 6 inches of the floor or to an approved location.
- Expansion tank on the cold supply (required where a check valve, pressure-reducing valve, or backflow preventer creates a closed system — most modern WA homes).
- Drain pan under the tank if it’s installed where a leak would damage finished space.
- Combustion air and venting correct for gas units (Type B vent, sealed combustion, or power-vent depending on model).
- Gas connector rated for water heater service (yellow flexible connector, sediment trap upstream).
- Electrical correct for electric tank or HPWH (10/2 wire on 30A breaker for standard electric; HPWH wiring per manufacturer spec).
The choice between replacement types — gas tank, electric tank, tankless, or heat pump water heater — has gotten more interesting in WA. Utility rebates and the federal Inflation Reduction Act tax credit have made HPWH net-cheaper than direct gas-to-gas replacement for many homeowners.
Why it matters to a homeowner
This is the most expensive plumbing line item most homeowners hit on a routine basis. Three areas to get right:
- Pull the permit. WA jurisdictions universally require a permit for water heater replacement, even like-for-like. Permit fees are $80–$200; the inspection catches missing seismic straps, wrong TPR discharge, missing expansion tank — items that hit you at sale if uninspected. See water heater permit.
- Get rebates and credits filed. PSE (Puget Sound Energy), Seattle City Light, Tacoma Power, and Snohomish PUD all offer HPWH rebates. The federal IRA §25C tax credit covers 30% of HPWH cost up to $2,000. A licensed installer should handle the rebate paperwork; if they won’t, that’s a sign to find someone else.
- Get multiple quotes — even on a leak. A leaking water heater is an emergency, but it’s not so urgent that you should accept the first quote without comparison. Shut off the water supply and the gas/electric, then take 24–48 hours for 2–3 written quotes. The cost difference between quotes for the same job often runs $1,000+.
Common variants and not the same as
- Like-for-like replacement vs. fuel switch. Like-for-like is fastest. Fuel switching (gas-to-electric, electric-to-HPWH, gas-to-tankless) adds scope: vent removal/install, electrical panel upgrade for HPWH (200A panel commonly required), gas line removal/cap, condensate drain for tankless.
- Replacement vs. repair. A 6-year-old tank with a failed thermostat or anode rod is a repair, not a replacement. A 13-year-old tank with sediment rumble is a replacement decision. See water heater thermostat and anode rod.
- Tank vs. tankless vs. HPWH. Tank: cheapest install, 10–12 year life. Tankless: higher install cost, 15–20 year life, endless hot water but limited flow rate. HPWH: highest install cost before rebates, often net-cheapest after rebates, 15–20 year life, slower recovery than tank but cheaper to run.
Common scams (and how to spot them)
- “Same-day install” pressure pricing. A plumber arrives at a leak, presents an inflated quote, claims work has to start today. Counter: shut off water and power yourself, get 2–3 written quotes over 24 hours, install tomorrow. The leak is not catastrophic once isolated.
- Skipping the permit “to save money.” Permits are cheap; uninspected installs cost you at sale or insurance claim time.
- Up-charge for “code-required” components that aren’t required at your house. Most modern WA homes do need the expansion tank because of a PRV or check valve in the system, but verify the installer can point at the specific reason — not “code requires it everywhere.”
- Cash deals with no invoice. No paper trail = no warranty, no rebate eligibility, no proof of work for a future buyer’s inspection.
- Lapsed L&I license. Confirm the contractor and bond on WA L&I’s Verify a Contractor page before any payment. See WA L&I license.
Cost ranges (WA, 2026)
| Type | Install cost | Typical life | Rebate notes |
|---|---|---|---|
| 50-gallon gas tank (like-for-like) | $1,800–$3,200 | 10–12 years | None typical |
| 50-gallon electric tank | $1,400–$2,500 | 10–12 years | None typical |
| Tankless gas | $4,500–$7,500 | 15–20 years | Limited utility rebates |
| Heat pump water heater (HPWH) | $4,500–$8,500 | 15–20 years | $1,500–$2,500 utility rebate + 30% federal credit (IRA §25C) |
Permit fees ($80–$200) and any panel-upgrade work for HPWH are additional.
When you’ll encounter this term
- A leak under or around the existing water heater
- Rumbling, banging, or popping noises at burner-on (sediment)
- Hot water runs out faster than it used to, or stays lukewarm at the tap
- A pre-purchase inspection flags a 12+ year old water heater
- Considering a gas-to-electric or gas-to-HPWH conversion as part of a remodel or for rebate access
Washington note
WA replacement requirements are uniform across jurisdictions for the items the inspector checks:
- Seismic strapping at upper third and lower third (WAC 51-50 / IRC P2801.7). Two strap kit, anchored into wall framing — not drywall.
- TPR discharge tube terminating within 6 inches of the floor (or to an approved exterior or pan location). Threaded — not soldered or glued. No traps in the discharge line.
- Expansion tank required where there is a closed system. Most homes built or remodeled since 1990 have a PRV at the main, which closes the system. Sized for tank capacity.
- Drain pan required when a leak could damage finished space (so basement utility room often yes; detached garage often no).
WA’s rebate landscape is the largest economic factor in modern replacement choices. PSE, SCL, Tacoma Power, Snohomish PUD, and several smaller utilities offer significant HPWH rebates that combine with the federal IRA §25C credit (30% of cost, up to $2,000). For many homeowners, an HPWH installed with rebates filed costs roughly the same out-of-pocket as a like-for-like gas tank — and runs cheaper for 15–20 years afterward.
Confirm current rebate amounts on your specific utility’s site before signing the install contract. Programs change.
DIY scope
Tank water heater swap is a moderate-difficulty DIY for an owner-occupant — the work itself is straightforward (shut-offs, drain, disconnect, set new, reconnect, fill, verify). The pieces homeowners trip on:
- Permit and inspection. Pull the permit yourself as the owner-occupant; schedule the inspection.
- Seismic strapping. Strap to framing, not drywall.
- TPR discharge. Threaded, downhill, terminating within 6 inches of floor or approved location.
- Expansion tank. Pre-charge to incoming static pressure, sized for tank capacity.
- Gas connector/sediment trap (gas units) or electrical connection (electric units) — code-correct sized.
When to call a pro: HPWH installs that need a panel upgrade; tankless installs that need new gas-line sizing or condensate routing; any fuel-switching project; any unit in a confined space with combustion-air requirements.