Guides / Water heaters · Updated
How old is my water heater?
Date codes from Bradford White's and Rheem's own pages, checked November 2026.
Short answer
The build date is hidden in the serial number on the rating label. On a Bradford White, the first letter is the year and the second the month (SG = July 2018). On a Rheem, the first four digits are month then year (1209 = December 2009).
Bradford White
Bradford White says "the first two characters of the serial number represent the year and month of manufacture." Year letters skip I, O, Q, R, U and V, so the 20 letters come round every 20 years: A is 2004 or 2024. Month letters run A to M, skipping I. After the two letters is a production number, seven digits long before December 2007 and eight after, which can help tell a 2005 heater from a 2025 one.
| First letter | Year | Second letter | Month |
|---|---|---|---|
| A | 2004 or 2024 | A | January |
| B | 2005 or 2025 | B | February |
| C | 2006 or 2026 | C | March |
| D | 2007 or 2027 | D | April |
| E | 2008 or 2028 | E | May |
| F | 2009 or 2029 | F | June |
| G | 2010 or 2030 | G | July |
| H | 2011 or 2031 | H | August |
| J | 2012 or 2032 | J | September |
| K | 2013 or 2033 | K | October |
| L | 2014 or 2034 | L | November |
| M | 2015 or 2035 | M | December |
| N | 2016 or 2036 | ||
| P | 2017 or 2037 | ||
| S | 2018 or 2038 | ||
| T | 2019 or 2039 | ||
| W | 2020 or 2040 | ||
| X | 2021 or 2041 | ||
| Y | 2022 or 2042 | ||
| Z | 2023 or 2043 |
Source: Bradford White, My Water Heater and FAQs. Bradford White publishes the table from 2004; older heaters follow the same 20-year cycle by our reading.
Rheem
Rheem says the serial on every water heater's rating label has ten characters. Its own example, 1209D01234, reads as month 12, year 09, plant line D and serial 01234: built December 2009.
Other brands
We couldn't find a date code published by A. O. Smith, State, Rinnai or Navien themselves, and the decoders elsewhere disagree with each other, so we haven't included them. Ruud has a serial lookup on its site. For any brand, the maker's support line can read the serial for you.
Replacing it?
Size the new one with the water heater size calculator, compare running costs with is a heat pump water heater worth it, and check your panel with the water heater circuit check.