How old is my State water heater?
Serial number age decoder for State tank water heaters: 6 format eras, the decode rule in plain English, transcribed tables, and the official lookup.
Type the serial from the data plate, not the model number. Nothing is sent anywhere; the tables are in this page.
Format example: 1210A002243
- State water heater serial numbers in the 2008 to present format encode the year as digits 1-2 (YY) after optional leading S and the week as digits 3-4 (source: building-center.org).
- Example: serial 1210A002243 decodes to week 10 of 2012.
- State water heater serial numbers in the before 2010 format encode the year as digits 2-3 (YY); century from ANSI date on plate and the month as letter 1 (A=Jan..M=Dec, I skipped) (source: building-center.org).
- Example: serial H765662231 decodes to August 1976.
- State water heater serial numbers in the before 2004 format encode the year as digits 3-4 (YY) and the month as letter 2 (A=Jan..M=Dec, I skipped) (source: building-center.org).
- Example: serial AF04A093001 decodes to June 2004.
- State's official lookup at statewaterheaters.com returns warranty status.
Format eras
- before 2010 VERIFIED
A#########digits 2-3 (YY); century from ANSI date on plate - before 2010 VERIFIED
A##A######digits 2-3 - 2008 to present VERIFIED
####A######digits 1-2 (YY) after optional leading S - before 2008 VERIFIED
AA##A######digits 3-4 - before 2004 VERIFIED
AA##A######digits 3-4 (YY) - 1970 to 1979 VERIFIED
A##-A-##-######2 digits between hyphens (78)
How to read the serial
before 2010 formatVERIFIED
Shape A######### · example H765662231 / M07A009387 · confidence medium
- Year
- digits 2-3 (YY); century from ANSI date on plate
- Week or month
- month = letter 1 (A=Jan..M=Dec, I skipped)
| Month code | Month |
|---|---|
| A | January |
| B | February |
| C | March |
| D | April |
| E | May |
| F | June |
| G | July |
| H | August |
| J | September |
| K | October |
| L | November |
| M | December |
Example: serial H765662231 decodes to August 1976.
before 2010 formatVERIFIED
Shape A##A###### · example E07A135491 · confidence medium
- Year
- digits 2-3
- Week or month
- month = letter 1 (A=Jan..)
| Month code | Month |
|---|---|
| A | January |
| B | February |
| C | March |
| D | April |
| E | May |
| F | June |
| G | July |
| H | August |
| I | September |
| J | October |
| K | November |
| L | December |
Example: serial E07A135491 decodes to May 2007.
Listed under A.O. Smith in the source; State is named in that format's family and the corporate link is an estimate, not a checked fact.
2008 to present formatVERIFIED
Shape ####A###### · example 1210A002243 / S1318 F000046 / 1836111786352 · confidence high
- Year
- digits 1-2 (YY) after optional leading S
- Week or month
- week = digits 3-4
- Plant
- letter after the 4 date digits (unpublished)
Example: serial 1210A002243 decodes to week 10 of 2012.
Listed under A.O. Smith in the source; State is named in that format's family and the corporate link is an estimate, not a checked fact.
before 2008 formatVERIFIED
Shape AA##A###### · example AF04A093001 / GG03-1495366-S29 · confidence medium
- Year
- digits 3-4
- Week or month
- month = letter 2 (A=Jan..)
- Plant
- letter 1
| Month code | Month |
|---|---|
| A | January |
| B | February |
| C | March |
| D | April |
| E | May |
| F | June |
| G | July |
| H | August |
| I | September |
| J | October |
| K | November |
| L | December |
Example: serial AF04A093001 decodes to June 2004.
Listed under A.O. Smith in the source; State is named in that format's family and the corporate link is an estimate, not a checked fact.
before 2004 formatVERIFIED
Shape AA##A###### · example AF04A093001 · confidence medium
- Year
- digits 3-4 (YY)
- Week or month
- month = letter 2 (A=Jan..M=Dec, I skipped)
- Plant
- letter 1 = factory code (dropped after July 2004)
| Month code | Month |
|---|---|
| A | January |
| B | February |
| C | March |
| D | April |
| E | May |
| F | June |
| G | July |
| H | August |
| J | September |
| K | October |
| L | November |
| M | December |
| Plant code | Plant |
|---|---|
| A | Jan |
| B | Feb |
| C | Mar |
| D | Apr |
| E | May |
| F | Jun |
| G | Jul |
| H | Aug |
| J | Sep |
| K | Oct |
| L | Nov |
| M | Dec |
Example: serial AF04A093001 decodes to June 2004.
1970 to 1979 formatVERIFIED
Shape A##-A-##-###### · example A20-H-78-015482 · confidence medium
- Year
- 2 digits between hyphens (78)
- Week or month
- month = letter between hyphens (H=Aug)
| Month code | Month |
|---|---|
| A | January |
| B | February |
| C | March |
| D | April |
| E | May |
| F | June |
| G | July |
| H | August |
| I | September |
| J | October |
| K | November |
| L | December |
Example: serial A20-H-78-015482 decodes to August 1978.
Listed under A.O. Smith in the source; State is named in that format's family and the corporate link is an estimate, not a checked fact.
Where the data plate is on a water heater
The rating plate is a large label on the side of the tank near the top or beside the control. The serial is printed on it, often beside the model number and the ANSI standard line.
General guidance, not brand-specific: the owner's manual or the installer can point to the exact spot. See the data plate guide.
For scale only: the InterNACHI Standard Estimated Life Expectancy Chart for Homes lists Water Heater (conventional) at 6 to 12 years of expected service (nachi.org). That chart is a guideline, not a prediction for your unit.
Open the official State lookup takes serial; returns warranty status; URL verified live
This site is a reference built from published tables. The manufacturer's own lookup wins whenever the two disagree.
What we could not confirm
- State is treated as sharing A.O. Smith's format because the source lists it in that family; the corporate relationship itself is an estimate.
- Current State serials (1210A002243 / S1318 F000046 / 1836111786352) are the A.O. Smith YYWW style. Two discontinued State-specific styles below. Warranty page is the AO Smith verification tool re-skinned (serial or reference number).