How Long Do Water Heaters Last?

Sources give 6 to 12, 8 to 12 and 10 to 15 years for a tank water heater. Here is how to find your unit's age, the signs it is failing, and what to do about a leak.

Last updated: 9 November 2026

Sources give three overlapping ranges for a storage-tank water heater: 6 to 12 years (InterNACHI's chart), 8 to 12 (Lennox) and 10 to 15 (a Department of Energy estimate for ideal conditions, as reported by Lennox). This page uses 8 to 12 years as a planning figure because it is Lennox's own range and sits inside InterNACHI's; it is not a consensus. The number that matters for your house is how old your tank already is, so this page also covers finding that out, the signs a heater is failing and what to do if it leaks. It covers conventional gas and electric storage-tank heaters. Tankless and heat pump models have different ranges and aren't covered here.

Where the figures come from

The sources don't say how they arrived at their numbers. Lennox describes 10 to 15 as the Department of Energy's estimate under ideal conditions and 8 to 12 as what most units in real homes reach. InterNACHI's chart says life expectancy varies with usage, weather, installation, maintenance and quality of materials, and that the mineral content of water can shorten the life of water heaters. It calls its figures guidelines, not guarantees.

Find your heater's actual age first

Before comparing yourself to any range, read the build date off the tank. Manufacturers print it, usually as letters and digits at the start of the serial number, on the rating plate. Where to find the serial number on a water heater shows where the plate sits, and how date codes work explains why one letter can mean two different years.

If your heater is one of these brands, you can type the serial straight into a decoder:

• Bradford White water heater age decoder
• A.O. Smith water heater age decoder

Other brands, or several appliances at once, start at the Appliance Age Finder. With the age in hand, the equipment remaining life calculator subtracts it from the InterNACHI range for you. The result is a planning window, not a failure date.

Buying a house? The seller's recollection of when the heater was installed is a weaker record than the plate. Checking the water heater's age when buying a house covers what to look at and what to ask.

What to make of the age you find

• Under 8 years. Nothing to do beyond recording the serial number and install date and keeping the receipt; a warranty claim usually needs them.
• 8 to 12 years. Check the base of the tank for moisture and start planning a replacement. Planning before it fails is usually calmer than deciding during a flood.
• Over 12 years. Past the range most sources give for real homes. Replace it on your own schedule, and have a plumber look at any leak or rusty hot water promptly.

If the heater fails well before 6 years, check the warranty and the installation date first. If you are unsure of the age, use the serial number rather than memory.

Signs a tank is failing

These come from Lennox and A.O. Smith.

• Moisture at the base. Lennox: "Any pooling or persistent moisture at the base of the unit is a call to action." A.O. Smith calls a leak from the base "often the first indication of a serious problem".
• Rust-coloured hot water. Lennox says discoloration from the hot-water tap is "a direct signal that the interior of your tank has corroded". A.O. Smith lists rust, cloudiness or a metallic smell.
• Noise. Lennox says banging, popping or rumbling during heating cycles is the sound of hardened sediment. A.O. Smith adds that sediment can weaken the tank over time.
• A cracked tank. A.O. Smith says it "will typically result in a full replacement of the water heater".

Moisture at the base, or rusty or discoloured hot water, at any age: have a plumber check it. At 8 years or more, also price a replacement.

Keeping a tank going longer

Inside a steel tank, a sacrificial anode rod corrodes in place of the tank. Wikipedia says that once it is completely corroded, "the steel tank will corrode much faster". Lennox says the rod "should be inspected every 3 to 5 years" and that the tank should be drained and flushed "once a year, or twice a year in hard-water areas". Your owner's manual, or the manufacturer's site for your model (for example Bradford White or A.O. Smith), gives the schedule for your unit. Bradford White says maintenance should be performed by a plumbing or HVAC professional.

If the tank leaks

1. If you smell gas, leave the house immediately and call your gas utility before doing anything else. On a gas unit, do not touch switches or light flames near a leak.
2. Water off. A.O. Smith says to close the cold water shut-off valve, the valve on the incoming cold line, usually with a handle and often marked blue.
3. Power or gas off. Switch off the heater's breaker (electric) or turn the gas shut-off valve on the pipe to the burner (gas). If there is standing water between you and the panel or switch, don't wade in: shut off the main breaker if you can reach it dry, or call the utility or an electrician.
4. Find where it's leaking. A.O. Smith notes that condensation can look like a leak, and that a dripping temperature-and-pressure relief valve or a leaking fitting are other possible sources. A.O. Smith says a leak from the bottom of the tank requires complete replacement since you can't repair a corroded tank; corroded fittings need professional replacement.
5. If the leak is from the tank itself, or you are not sure where it is coming from, call a plumber and get replacement quotes.

Sources

1. InterNACHI's Standard Estimated Life Expectancy Chart for Homes. Accessed 9 November 2026.
2. Wikipedia, Storage water heater. Accessed 9 November 2026.
3. Lennox, how long can a water heater last. Accessed 9 November 2026.
4. A.O. Smith, water heater leaking. Accessed 9 November 2026.
5. A.O. Smith, what to do when your hot water heater is leaking. Accessed 9 November 2026.
6. Bradford White, my water heater. Accessed 9 November 2026.

Furnaces and air conditioners follow the same logic: see how long a furnace lasts and how long air conditioners and heat pumps last.