State water heater age from the serial number
State Water Heaters is an A. O. Smith brand, so current State serials start with the year and the week. Type yours and the tool returns the build date.
State water heater age finder
Paste the serial number exactly as printed, letters included. Spaces and dashes are ignored.
Results are estimates of the manufacture date. The rating plate and the manufacturer’s support line are the authority.
Where to find the State water heater serial number
The State water heater serial number is on the rating plate, the label on the side of the tank, and the State water heater age is in it. Photograph the plate and copy the serial carefully. A wrong letter or digit changes the date.
State is an A. O. Smith brand, which matters for decoding. The Building Intelligence Center lists State’s codes the same way as A. O. Smith’s, and A. O. Smith’s own service and warranty guide publishes the current rule. So most of what applies to the A. O. Smith serial number applies here.
How the State water heater serial number works
On current units, the first two digits are the year and the next two are the week of the year, from 01 to 53. The rest is a sequence number. So 1735107397129 is week 35 of 2017, and 1210A002243 is week 10 of 2012. A letter can sit inside the sequence. That year-and-week pair is the State water heater date code.
Older State units use letters. The simplest style is a month letter followed by a two-digit year. Month letters run A for January through M for December and skip I. Another style puts a factory letter first and the month letter second, as in AF04A093001, which is June 2004.
- Current: year, then week, then sequence
- Older: month letter, then two-digit year
- Older still: factory letter, month letter, year
Five worked examples
These are documented State serials from the Building Intelligence Center. In H765662231, H is August and 76 is the year. The tool treats two-digit years as 2000s unless that would be in the future, so 76 becomes 1976.
| Serial | Pattern | What the tool shows |
|---|---|---|
| 1735107397129 | Year + week (current) | Week 35 of 2017 |
| 1210A002243 | Year + week (current) | Week 10 of 2012 |
| M07A009387 | Month letter + year | December 2007 |
| H765662231 | Month letter + year | August 1976 |
| AF04A093001 | Factory letter, month letter, year | June 2004 |
A two-digit year is ambiguous by a century. The tool assumes the 2000s unless that date would be in the future.
What the tool cannot read
The current format is well supported. The older letter formats rest on third-party references, so we rate them medium confidence.
- InterNACHI describes the State code as a month letter followed by a two-digit year. Its short example, J89, fits that pattern, but the tool needs the full serial to match.
- Letter styles that differ from the three above come back as “can’t date”.
- A serial with a plausible year but a week above 53 is rejected.
When the tool says it cannot date a serial, look for a printed date on the plate or contact the manufacturer’s support line with the model and serial.
Brand notes: State, A. O. Smith and the shared code
State and A. O. Smith are separate brand names on one code, so a State serial and an A. O. Smith serial from the same week look alike. If you are auditing a portfolio with both, you can decode them the same way.
That is also why the tool has a separate State entry: people search for it by brand name. If your plate carries the name American or Whirlpool, those brands are covered on separate pages: Whirlpool water heaters use a year-and-week rule too, but the link between that brand and A. O. Smith comes from third-party references.
How long does a State water heater last?
The finder measures age against a typical water heater life of 12 years. We did not find a published lifespan specific to State, so the useful numbers are the general ones. The NAHB study lists 10 years for a gas tank and 11 for an electric tank. Rheem gives 8 to 12 years for a conventional tank. The Department of Energy puts storage tank water heaters at 10 to 15 years.
A unit near 12 years is a unit to inspect, not a unit to replace on schedule. Look at the base for leaks, the water for rust and the repair history. Our water heater lifespan guide covers the signs.
Put the State age on the unit's record
A week number on a plate is easy to lose. In Invendoory, a water heater is an item in the unit’s inventory with its serial, install date, expected life and a photo tagged as the serial plate. The life-used bar shows how much of its life is gone, in green, amber or red.
That lets a supervisor see which tanks to replace first. See the asset inventory, the water heater age guide or the full Appliance Age Finder.
State water heater age questions
How do I read a State water heater serial number?
On current units, the first two digits are the year and the next two are the week, from 01 to 53. 1735107397129 is week 35 of 2017. Older units use a month letter and a two-digit year.
Is State the same as A. O. Smith?
State Water Heaters is an A. O. Smith brand, and it uses the same serial code. A. O. Smith’s service and warranty guide publishes the current year-and-week rule, and State’s codes are listed the same way.
Why is the result a week and not a month?
Current State serials carry the week of manufacture. The tool shows it as printed, for example week 35 of 2017, and uses it to estimate the age in years.
What does a letter at the start of a State serial mean?
On older units, a single letter is the month, A for January to M for December, skipping I, followed by a two-digit year. A serial starting with two letters carries a factory letter, then the month letter.
What if my State serial can't be dated?
Check that you copied the serial, not the model number. Some old formats are not covered. Look for a printed manufacture date on the plate or contact the manufacturer’s support line with the model and serial.
Sources
- Building Intelligence Center – State water heater age
- A. O. Smith Service and Warranty Guide, July 2024
- InterNACHI Water Heater Dating Chart
- NAHB and Bank of America Home Equity, Study of Life Expectancy of Home Components (2007)
- U.S. Department of Energy, Energy Saver Guide (2022)
- Rheem, Water Heater Lifespan: When to Repair vs. Replace
Checked October 2026.
Keep the age of every water heater on file
The finder dates one tank. Invendoory keeps the serial, install date and life used for every water heater in every unit. Open the live demo, no signup needed.