Water Heater Replacement Cost: Full Breakdown

Quick Answer

Replacing a tank water heater costs $900–$1,800 installed. A tankless unit runs $1,500–$3,500 installed. The difference comes down to unit cost, gas line work, and venting requirements.

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Water heaters don't fail at convenient times. When yours starts leaking or stops producing hot water, you need a replacement fast — which is exactly when making a rushed decision costs money. Here's what water heater replacement actually costs and what variables move the price.

Tank vs. Tankless: The Core Cost Split

The choice between tank and tankless is the biggest cost driver for a replacement.


**Tank water heaters** (conventional storage units) are the most common residential type. A 40-gallon natural gas unit costs $450–$700 for the unit itself. Labor to install runs $300–$600 depending on your area, bringing the total to $900–$1,500 for a straightforward swap. Electric tank units are slightly cheaper on the unit side ($350–$550) but often similar in total installed cost.

**Tankless water heaters** (on-demand units) cost more upfront — $700–$1,500 for a gas unit — but use 20–35% less energy over time. Installation is more involved because tankless units require larger gas supply lines (often ¾" instead of ½"), dedicated venting that differs from traditional flue venting, and sometimes electrical upgrades. Total installed costs run $1,500–$3,500.

For a two-bathroom home with average hot water demand, the tankless premium usually pays back in 7–12 years through energy savings. If you're staying in the home long-term, it's often worth it.

What Drives Installation Cost

**Like-for-like swap.** Replacing the same type of heater in the same location is the cheapest scenario. The plumber disconnects the old unit, drains it, removes it, and connects the new one to existing supply lines and the existing flue or vent. This takes 2–4 hours. Expect $900–$1,400 total in an average market.

**Location change.** Moving a water heater to a different location means running new supply lines, new gas lines, and new venting. Add $300–$800 to the base install cost.

**Gas line upgrades.** Tankless units need higher BTU input and larger gas supply lines. If your existing gas line is undersized, a plumber or gas contractor needs to run a new line — typically $300–$700 depending on the run length.

**Venting changes.** Tankless units use direct-vent or power-vent systems that require different flue configurations than traditional tank units. New venting through an exterior wall adds $200–$500.

**Expansion tanks.** Many water departments now require a thermal expansion tank when installing a new water heater. This $50–$150 part protects the water system from pressure spikes. Some plumbers include this automatically; others charge separately.

Use our [plumbing cost calculator](/plumbing-cost-estimator) with "Water Heater Installation" selected to get a full estimate for your region and complexity level.

Permit Requirements

Water heater replacements require a permit in most jurisdictions. Permits run $50–$400 depending on your municipality. After installation, an inspector will verify the venting, gas connections, and pressure relief valve.

Some homeowners skip the permit on a like-for-like swap. This is risky — it can affect your homeowner's insurance claim if the unit causes water damage, and it may need to be disclosed when you sell the home. Read our [plumbing permit guide](/blog/plumbing-permits-guide) for more on when permits are required.

Signs Your Water Heater Needs Replacing

- Age: tank units last 8–12 years, tankless 15–20 years

- Rust-colored water from hot taps

- Rumbling or popping sounds (sediment buildup)

- Visible corrosion or rust on the tank

- Standing water around the base

- Inconsistent hot water temperature

Repairs are worth it if the unit is under 7 years old and the repair is under $300. Once a tank water heater hits 10 years, replacement usually makes more financial sense than repair.

Getting Quotes

Call at least two licensed plumbers when replacing a water heater. Ask each one:

1. What brand and model are you installing?

2. Does the quote include permit, disposal of the old unit, and expansion tank if required?

3. What's your labor rate if the installation takes longer than expected?

Itemized quotes are easier to compare than bundled lump-sum quotes. A plumber who can't tell you the unit cost separately from labor is harder to evaluate.

Read our guide on [how much plumbers charge](/blog/how-much-does-a-plumber-cost) for current regional labor rates.