How Long Do Water Heaters Last? Lifespan by Type

A water heater rarely dies without warning, but the warnings are easy to miss because the heater lives in a basement, garage or closet. Knowing its age and what to look for lets you replace it before it floods the floor.

Lifespan by type

InterNACHI’s life expectancy chart lists 6 to 12 years for conventional tank heaters, while the Department of Energy describes 10 to 15 years for storage water heaters. The difference comes down to water quality and maintenance: a flushed tank in soft water outlasts a neglected tank in hard water by years. The DOE describes tankless heaters as lasting more than 20 years.

The warranty is a useful clue. Tank heaters are commonly sold with 6, 9 or 12-year tank warranties, and the longer-warranty models usually have thicker insulation, larger or extra anode rods and better components.

How to find your water heater’s age

The age is printed on the rating plate, the large sticker on the side of the tank, but rarely as a plain date. It is encoded in the serial number, usually in the first four characters as a combination of month and year. Because each manufacturer uses its own format, the most reliable approach is:

1. Photograph the rating plate, including the brand, model number and serial number.
2. Look up the brand’s serial number guide on the manufacturer’s website, or call its customer service line.
3. Write the installation year on the tank with a marker for next time.

Signs a water heater is near the end

1. Water around the base.Act now

   Rule out a loose fitting at the top or the drain valve. A leak from the tank body itself means the steel has corroded through. It will not get better; plan the replacement immediately.

2. Rusty or discolored hot water.

   If only the hot water is discolored, the tank or its anode rod may be corroding. Rusty water from both taps points to your pipes or water supply instead.

3. Rumbling that flushing will not stop.

   Hardened sediment that will not flush out means the tank is working harder every year. Read what water heater popping means.

4. Hot water running out sooner.

   Sediment takes up space and a failing element or thermostat heats less water.

5. Age past 10 years.

   Not a failure by itself, but the point to start budgeting and checking for leaks regularly.

How to make a water heater last longer

• Flush it every year. Removing sediment protects the tank bottom and keeps efficiency up.
• Check the anode rod every three to four years, as the Department of Energy suggests. The rod corrodes instead of the tank. Once it is mostly gone, the tank starts corroding. Replacing a rod is far cheaper than replacing a heater.
• Keep the temperature at 120°F (49°C). The setting most energy agencies recommend saves energy, slows mineral buildup and reduces scald risk.
• Install an expansion tank if your plumbing has a closed system. When a check valve or pressure regulator prevents expanding water from flowing back to the street, pressure spikes stress the tank. Many codes require an expansion tank in this case.
• Soften very hard water. Less scale means less sediment and slower anode use.

Repair or replace?

Repairs make sense when the tank is dry and the part that failed is cheap and replaceable: a heating element, thermostat, thermocouple, igniter or gas control. A leaking tank always means replacement. For anything in between, our repair or replace calculator weighs the quote against the heater’s age and expected life.