How long do water heaters last?

Knowing how old your water heater is helps you decide whether a problem is worth repairing. The age is usually printed on the label, or coded into the serial number.

Tank heaters wear out mainly because the tank corrodes. Tankless heaters have no tank to corrode, so parts wear out first and can usually be replaced.

Typical lifespan by type

How long does a tankless water heater last?

The U.S. Department of Energy notes that most tankless water heaters have a life expectancy of more than 20 years, compared with about 10 to 15 years for storage tank heaters. Because there is no tank to rust through, a tankless heater usually ends its life when a major part such as the heat exchanger fails and repair no longer makes sense.

Hard water is the biggest threat. Scale builds up in the heat exchanger, causing overheating codes and lukewarm water. Annual descaling, more often with hard water, and cleaning the inlet filter keep it running; see our descale a tankless water heater guide. If a major part fails on an older unit, compare the repair against our tankless water heater installation cost guide.

How to find your water heater's age

Look for a manufacture date on the rating label. If there is none, most brands encode the year and month in the first four characters of the serial number. The pattern differs by brand, so check the manufacturer's serial number guide.

Signs it is near the end

• Rusty or discolored hot water
• Rumbling that continues after flushing the tank
• Water around the base that comes from the tank
• Hot water running out much faster than it used to

How to make it last longer

Flush a tank heater once a year, check the anode rod every few years, and keep the temperature around 120°F. Descale a tankless unit once a year, or more often with hard water.