How much does it cost to replace a water heater in Ontario?

Water heater replacement is one of the more predictable HVAC costs in Ontario — but the range is wide because "a water heater" covers everything from a basic 40-gallon gas tank to a fully vented condensing tankless system. Here's what actually drives the number on your quote, and how owning versus renting changes the math in a province where rental is unusually common.

Typical installed costs in the GTA

• Gas or electric tank water heater: $1,200–$2,500 installed, depending on size and venting
• Tankless (on-demand) water heater: $3,500–$6,500 installed, including gas-line and venting work
• Minor repairs instead of replacement: $150–$800, worth considering if the unit is under 8 years old
• Diagnostic service call: $90–$150, typically credited toward the work if you proceed

What drives the price

• Tank size and fuel: a 50-gallon gas tank costs more than a 40-gallon, and power-vented models add to the price
• Venting changes: switching to power-vent or condensing tankless means new PVC venting and a condensate drain
• Gas line: a tankless often needs the line upsized from ½" to ¾", adding $300–$1,000 — see our tankless cost guide
• Code upgrades: expansion tanks, drain pans, and seismic strapping where required
• Removal and disposal of the old unit, which a professional install includes

Owned vs. rented — and the buyout question

Roughly half of GTA and Hamilton homes pay a monthly water heater rental fee, so before you replace, find out whether you actually own your current unit. If it's rented, you'll likely owe a buyout to end the contract — often a few hundred dollars based on the tank's age — plus possible removal or early-termination charges. Get that figure in writing, then compare buyout-plus-new-owned-unit against years of continued rental payments. Since the 2024 ban on registering Notices of Security Interest (NOSI) on title, rental companies can no longer attach these contracts to your home's title, which has made switching to an owned unit cleaner. Our breakdown of renting vs. buying walks through the full lifetime math.

Same-day replacement when a tank fails

A leaking or dead water heater rarely waits for a convenient time. Most standard gas and electric tank swaps can be completed same-day across the GTA and Hamilton, since the equipment is stocked locally. Tankless conversions take longer when gas-line or venting work is involved. If you're deciding between fixing and replacing an older unit, our repair-vs-replace analysis helps you avoid sinking money into a tank near the end of its life.

ZK Mechanical replaces tank and tankless water heaters across the GTA and Hamilton, with flat upfront pricing and financing to spread the cost. Request a free quote or call (647) 801-1252 — we'll also compare any replacement against your current rental payment.