How Long Do Water Heaters Last? Tank, Tankless, Heat Pump

The Short Answer: A tank water heater usually lasts about 8 to 15 years. The U.S. Department of Energy puts storage and heat-pump heaters at about 10–15 years and tankless at about 20. A. O. Smith says 8–12 years for tanks and 15–20 for tankless. ENERGY STAR suggests planning a replacement once a heater passes 10 years, before it fails.

Expected life by type

The DOE figures come from its Energy Saver guide, Which water heater is right for you? (opens in a new tab), and its tankless page (opens in a new tab). DOE has taken those pages down, so the links go to archived copies from June 2026. A. O. Smith’s figures come from its pages on repair or replace (opens in a new tab) and how long water heaters last (opens in a new tab). The 8–12-year tank figure is based on the manufacturer’s suggested service life.

These are averages. Some tanks fail before 8 years and some run past 20. The ranges are a planning guide, not a deadline.

What makes one last longer than another

A. O. Smith lists water quality, maintenance, installation quality and household demand as the factors that affect a heater’s life:

• Water quality. Sediment and corrosion are what shorten a tank’s life. On tankless units, A. O. Smith calls hard water the biggest threat, because mineral scale builds up in the heat exchanger.
• Maintenance. Tankless heaters need periodic descaling in hard water. Our Navien error codes page shows how a heater flags that.
• Installation. A heater installed and vented to the manufacturer’s instructions, and sized for the household, isn’t pushed beyond what it was designed for.
• Demand. A heater that runs near its limit every day cycles more than one sized with room to spare.

What the warranty tells you

The tank warranty is the manufacturer’s own statement of how long it stands behind the tank, so it’s a useful clue to the design life:

• Standard tanks: 6-year tank and parts warranties are common on entry models, for example Rheem’s Performance gas tanks (opens in a new tab) and A. O. Smith’s ProLine GCR models (opens in a new tab). Bradford White’s warranty document (opens in a new tab) says its glass-lined tank warranty “can be 1, 6, 8 or 10 years,” depending on the model, with parts covered for 6.
• Longer-warranty tanks: A. O. Smith’s sheet notes a 10-year tank and parts version of the same models, and Rheem’s Performance Platinum (opens in a new tab) tanks carry a 12-year tank and parts warranty.
• Heat pump tanks: to be ENERGY STAR certified, a heat pump water heater needs at least a 6-year warranty on the sealed system, according to the ENERGY STAR specification (opens in a new tab). Many models carry longer warranties.
• Tankless: heat exchanger warranties are longer. Rheem’s residential tankless warranty (opens in a new tab), which also covers Ruud and Richmond, gives 15 years on the heat exchanger in a single-family home and 5 on parts. It gives less with an uncontrolled recirculation loop or space heating, and voids all warranties after 12,000 hours of operation.

A 6-year heater and a 12-year heater may look alike. The model number and the warranty sheet tell them apart.

Signs it’s wearing out

ENERGY STAR (opens in a new tab) suggests considering replacement once a heater is more than 10 years old. It lists these signs of a heater near the end:

• Corrosion on the tank or at the fittings
• Water leaking from the tank, or from joints or seams
• Rusty hot water
• Rumbling or banging noises, often from sediment

A leak from the tank shell itself always means replacement. Many puddles come from a fitting, the drain valve or the relief valve instead, so find the source first; see water heater leaking. Rumbling on its own is often sediment rather than failure; see water heater sounds like rocks.

How to tell how old yours is

Most heaters carry the build date in the serial number on the rating plate. Our serial number decoder reads it for Rheem, A. O. Smith, Bradford White, Rinnai and other brands. There are dedicated guides for Bradford White and A. O. Smith, whose codes are the most often misread.

Repair or replace?

• Under about 8 years, no tank leak: usually worth repairing. Thermostats, elements, igniters, gas controls and valves are replaceable parts, and the heater may still be under warranty.
• About 8–12 years: weigh the repair. A minor part is still reasonable; a gas control or an element plus thermostat on a tank showing rust may be better money toward a new heater.
• Past about 12 years, or any tank leak: plan on replacement. On tankless units, a failed heat exchanger out of warranty is usually the point to replace.

Frequently Asked Questions

Q: Do electric water heaters last longer than gas? A: DOE gives the same 10–15-year range for both kinds of storage tank. In both, the tank is what usually ends the heater’s life. Elements, thermostats and gas controls can be replaced.

Q: My water heater is 15 years old and works fine. Should I replace it now? A: It’s past the typical range, so plan for it: check for rust at the base and the fittings, and know where the cold-water shutoff is. Replacing on your schedule avoids an emergency purchase after a leak.

Q: Does a tankless really last twice as long? A: Both give tankless heaters longer lives: DOE says about 20 years for tankless versus 10–15 for tanks, and A. O. Smith says 15–20 versus 8–12. That depends on maintenance: in hard water, a tankless that is never descaled can fail much sooner.