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How old is my American water heater?

Type the serial number from the American label to see when it was built. American units are built by American Water Heater, an A.O. Smith company, so the serials follow that company's format.

Example

0452121925

04Year: 04 = 2004
52Week: 52 (around December)

Built Week 52 of 2004 (around December)

21 years, 10 months old

Past typical life. Past the usual 6 to 12 year lifespan. Watch for rust-colored hot water, rumbling or popping from the tank, and moisture around the base.

Plan the replacement

Plan the replacement before it fails. A failed tank can release its full contents onto the floor.
Check the base and the fittings on top for moisture or rust now, and keep checking.
Know where the cold water shutoff above the tank is, so you can stop a leak quickly.
Some home insurers ask the age of the water heater, and in Florida a 4-point inspection flags tanks over 10 years. Check before you renew or buy a house.
Tank warranties usually run 6 to 12 years. Coverage usually counts from the install date or from a few months after the build date, so the build date is a good guide.

How this was read

The first two digits, 04, are the year: 2004.
The next two digits, 52, are the week of the year, so about December.

Format: Year and week. Sources: CPSC 2019 recall listing American, Whirlpool and U.S. Craftmaster, InterNACHI water heater dating chart.

Reading a American serial number

American Water Heater, of Johnson City, Tennessee, has started serials with the year and week since at least 1989. Some labels print "YEAR WEEK" right under the number.

A.O. Smith bought the company in 2006.

About American

Before 2006 American Water Heater belonged to GSW, a Canadian company. A.O. Smith bought GSW for about $340 million in cash.
American sold its own water heaters as American PROLine and U.S. Craftmaster.
American was the only water heater supplier to Lowe’s in 2006, building the Whirlpool-brand units.

Sources: A. O. Smith Corporation News Release dated April 3, 2006 (SEC exhibit 99.1), A.O. Smith buys American Water Heater parent (Contractor, 2006)

Year and week

Used 1989 to today. Example: 1104T403904

American Water Heater, which also built Whirlpool and U.S. Craftmaster units, prints the year (2 digits) then the week (2 digits) at the start of the serial. Some labels print "YEAR WEEK" under it.

Worked example: 0452121925 was built Week 52 of 2004 (around December), so it is 21 years, 10 months old as of October 2026.

Sources: CPSC 2019 recall listing American, Whirlpool and U.S. Craftmaster, InterNACHI water heater dating chart

American recalls

Recalls from the U.S. Consumer Product Safety Commission that name American. Whether a unit is included depends on its model and build date; the checker above flags matches.

Year	Recall	Hazard
2018	A.O. Smith Ultra-Low NOx gas water heaters	The burner screen can tear and the burner can overheat a wood floor.

Standing at the unit? Use your phone

Point your phone’s camera at this code. The scanner opens and reads the label for you.

Same serial number format as American: Kenmore, U.S. Craftmaster, Whirlpool.

Formats on this page were last checked against their sources in October 2026. American is a trademark of its owner. This page is independent and not affiliated with or endorsed by American. For warranty questions, contact American directly.

Where the serial is on a American

The rating label is on the front of the tank above the gas valve or the upper thermostat cover.

The label is a sticker on the side of the tank, usually above the gas valve or the upper thermostat cover. On units squeezed into a closet it often faces the wall, so a phone photo is easier than reading it by eye.