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How old is my State water heater?

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

Scan insteadWhere is the label?

Example

S1318F000046
  • 13Year: 13 = 2013
  • 18Week: 18 (around May)

Built Week 18 of 2013 (around May)

13 years, 5 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
  1. Skip the leading S. It is a plant or product code.
  2. The first two digits, 13, are the year: 2013.
  3. The next two digits, 18, are the week of the year, so about May.

Format: Year and week. Sources: CPSC 2019 A.O. Smith recall (year and week), CPSC 2008 A.O. Smith and State recall (month letters), A.O. Smith Service and Warranty Guide (PDF).

Reading a State serial number

A.O. Smith bought State Industries in 2001. State serials have followed the A.O. Smith formats since then: year and week on newer units, a month letter and year on older ones.

About State

  • State began as State Stove & Manufacturing Co. in Nashville, Tennessee, and made only water heaters by 1948.
  • State moved its factory to Ashland City, Tennessee, in 1961. Its headquarters is still there.
  • When A.O. Smith agreed to buy it in 2001, State also ran plants in Franklin and Cookeville, Tennessee, and Charlotte, North Carolina.

Sources: State Industries co-founder, John R. Lindahl Sr. (Contractor), A.O. Smith To Acquire State Industries (Supply House Times), About Us | State Water Heaters

Year and week

Used about 2008 to today. Example: 1719106145074

The first two digits are the year and the next two are the week of the year. A letter may come first or in the fifth position; it is a plant code. A CPSC recall notice confirms this reading: "the first four digits represent the year and week of production".

Worked example: S1318F000046 was built Week 18 of 2013 (around May), so it is 13 years, 5 months old as of October 2026.

Sources: CPSC 2019 A.O. Smith recall (year and week), CPSC 2008 A.O. Smith and State recall (month letters), A.O. Smith Service and Warranty Guide (PDF)

Plant letter, month letter and year

Used through June 2004. Example: MK890054977H43

The first letter is the factory, the second letter is the month (A is January, I is skipped), and the next two digits are the year. MK89 means October 1989.

Worked example: MK89-0054977-H43 was built October 1989, so it is 37 years old as of October 2026.

The full lookup tables are on the A.O. Smith page, since State uses the same code.

Sources: CPSC 2019 A.O. Smith recall (year and week), CPSC 2008 A.O. Smith and State recall (month letters), A.O. Smith Service and Warranty Guide (PDF)

Month letter and year

Used july 2004 to about 2008, and older State units. Example: L07A071460

The first letter is the month (A is January, I is skipped) and the next two digits are the year. L07 means November 2007.

Worked example: L07A071460 was built November 2007, so it is 18 years, 11 months old as of October 2026.

The full lookup tables are on the A.O. Smith page, since State uses the same code.

Sources: CPSC 2019 A.O. Smith recall (year and week), CPSC 2008 A.O. Smith and State recall (month letters), A.O. Smith Service and Warranty Guide (PDF)

1970s series, month letter and year

Used 1970s to early 1980s. Example: 800M7209519

A three-character series code comes first, then the month letter and the year, like 800-M-72-09519 for December 1972.

Worked example: 800-M-72-09519 was built December 1972, so it is 53 years, 10 months old as of October 2026.

The full lookup tables are on the A.O. Smith page, since State uses the same code.

Sources: CPSC 2019 A.O. Smith recall (year and week), CPSC 2008 A.O. Smith and State recall (month letters), A.O. Smith Service and Warranty Guide (PDF)

State recalls

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

YearRecallHazard
2018A.O. Smith Ultra-Low NOx gas water heatersThe burner screen can tear and the burner can overheat a wood floor.
2008A.O. Smith and State 75-gallon gas water heatersVent gases can get too hot and start a fire, or leak carbon monoxide into the room.
2005A.O. Smith 75-gallon propane water heatersSoot can build up on the burner and start a fire.
2004White-Rodgers controls on propane and convertible gas water heatersThe control can open slowly, so soot builds up on the burner and can start a fire.