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How long do water heaters last?

A tank water heater typically lasts 8 to 12 years, according to Rheem, and the U.S. Department of Energy puts the average life of a storage water heater at around 15 years. Tankless water heaters last longer: ENERGY STAR gives them a life expectancy of 20 years. To know where yours stands, find its build date in the serial number on the rating plate.

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Why do the numbers differ?

They measure different things. Rheem’s 8 to 12 years is what a manufacturer calls a typical service life. The Department of Energy’s figure is a statistical average across every storage water heater in its analysis, including the long-lived ones, so it runs higher. Both are averages: any one tank can fail sooner or last well beyond them.

How long do tankless water heaters last?

Longer than tanks. ENERGY STAR gives gas tankless water heaters a life expectancy of 20 years, and Rheem says tankless units can last 15 to 20 years or more with proper care.

Does the warranty tell you how long a water heater will last?

Not directly, but it tells you what the maker stands behind. Bradford White’s residential tank warranties run 1, 6, 8 or 10 years depending on the model, and the model number on the rating plate says which one you have. A longer warranty usually means a better-built tank, not a guaranteed life.

How do I find out how old my water heater is?

Read the serial number on the rating plate, the label on the side of the tank. Most manufacturers code the build date into it, but each does it differently:

  • Bradford White: the first two letters are the year and month.
  • A.O. Smith: the first four digits are the year and week.
  • Lochinvar: the first four digits are the year and week on tanks made since 2011.

The build date is usually a little earlier than the install date, since a water heater can sit in a warehouse before it’s installed.

Sources

  1. Rheem Manufacturing Company, Water Heater Lifespan: When to Repair vs. Replace. Traditional tank water heaters typically last 8 to 12 years; tankless water heaters can last 15 to 20 years or more with proper care.. Checked October 19, 2026.
  2. U.S. Department of Energy, Energy Conservation Program: Energy Conservation Standards for Consumer Water Heaters (final rule, April 2024). DOE estimates the average product lifetime to be around 15 years for storage water heaters.. Checked October 19, 2026.
  3. ENERGY STAR (U.S. EPA and DOE), Save More with ENERGY STAR Gas Tankless Water Heaters. Tankless water heaters have a life expectancy of 20 years.. Checked October 19, 2026.
  4. Bradford White Corporation, Limited Residential Water Heater Warranty (238-39699-00). Bradford White’s glass-lined tank warranty is 1, 6, 8 or 10 years from installation, depending on the model.. Checked October 19, 2026.

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Related pages

How long does a furnace last?

Most manufacturers put a furnace’s typical life at 15 to 20 years: Carrier, Lennox and Trane all use that range, and Bryant says 15 to 25. The U.S. Department of Energy estimates the average life of a gas furnace at 21.5 years. ENERGY STAR suggests having heating equipment evaluated once it’s more than 10 years old. The serial number on the rating plate tells you how old yours is.

How old is my Bradford White water heater?

On a Bradford White water heater, the first two letters of the serial number are the year and the month it was built. The first letter is the year, on a 20-year cycle, and the second is the month, from A for January to M for December. A serial that starts JC was built in March 2012. The serial is on the rating plate on the side of the tank.

How old is my A.O. Smith water heater?

On a current A.O. Smith water heater, the first two digits of the serial number are the year it was built and the next two are the week. A serial that starts 1719 was built in week 19 of 2017, around mid-May. The serial is on the rating plate on the tank, and the QR code on the same plate shows the serial and warranty status when you scan it.

How old is my Lochinvar water heater or boiler?

On a Lochinvar tank water heater made since 2011, the first two digits of the serial number are the year it was built and the next two are the week. A serial that starts 1142 was built in week 42 of 2011. Current Lochinvar boilers use the same year-then-week order, except units built in 2015, which put the week first. Older units use letter codes.