Water heater age lookup
Where to find the serial number
- Tank heaters: the rating plate or sticker on the side of the tank, usually near the gas control or the upper access panel on electric units.
- Tankless: a label on the side or bottom of the cabinet.
- Look for a line labeled Serial No. or S/N. The model number is a different line, so don’t use it.
- Some labels print the manufacture date directly. If yours does, that beats any decoding.
What your water heater’s age means
| Age (tank) | What it usually means | What to do |
|---|---|---|
| 0–5 years | Early in its life | Repair almost anything. Check the anode rod at year 3–5. |
| 6–9 years | Mid-life | Repair if the cost is under about half the price of a new heater. Flush it yearly. |
| 10–12 years | Near the typical 8–12 year lifespan | Budget for replacement. Avoid big repairs. |
| 13+ years | Past typical lifespan | Plan a replacement before it fails. Leaks often start without warning. |
Tankless units often last 15–20 years, so double these ranges for a well-maintained tankless heater. Not sure? Try our repair or replace calculator.
How each brand dates its water heaters
| Brand | Date code | Example |
|---|---|---|
| Rheem, Ruud, Richmond (and older GE tanks) | Skip leading letters. The next 4 digits are month + year (MMYY). Newer serials use week + year. | RH 0806B17262 = Aug 2006 |
| A.O. Smith, State | Newer: first 4 digits = year + week (YYWW). Older: a month letter (A=Jan … M=Dec, no I) + 2-digit year. If there are two letters, use the second. | 1210A002243 = week 10, 2012G04… = July 2004 |
| Bradford White | 1st letter = year (repeats every 20 years), 2nd letter = month (A=Jan … M=Dec, no I). | JM… = Dec 1992 or 2012 |
| American, Whirlpool, U.S. Craftmaster | First 4 digits = year + week (YYWW). | 1104T403904 = week 4, 2011 |
| Rinnai | Since 2009: 1st letter = year (A=2009, B=2010…), 2nd = month. | BL… = Nov 2010 |
| Navien | Characters 6–7 = year, 8 = month (X/Y/Z = Oct/Nov/Dec). Hyphenated serials contain YYYYMMDD. | 7414C14X… = Oct 2014 |
Sources: U.S. CPSC recall notices (A.O. Smith letter format, Navien date block), the InterNACHI water heater dating chart, building-center.org and InspectAPedia age guides. Manufacturers don’t publish decoding guides for every format, so treat medium- and low-confidence results as estimates and confirm with the label or the manufacturer. Kenmore, GE (newer) and Lochinvar heaters were made by several manufacturers, so we don’t decode them automatically.
Frequently asked questions
How do I tell how old my water heater is?
Find the serial number on the rating label (usually on the side of the tank), then decode it with the tool on this page. Many labels also print a manufacture date directly. If yours does, use that.
How long does a water heater last?
Tank water heaters typically last about 8–12 years, depending on water quality and maintenance. Tankless units often last 15–20 years with regular descaling.
Should I replace a 10-year-old water heater?
Not automatically. If it’s dry, heating well and not rumbling, you can keep it and plan ahead. If it needs a major repair, or there’s rust or water at the base, replacing it is usually the better value.
Why does the tool show more than one possible date?
Some brands use codes that repeat. Bradford White’s year letters, for example, cycle every 20 years. We show the most recent date that makes sense first. The label’s style, the warranty sticker or the install paperwork can confirm which one is right.
Where is the serial number on a water heater?
On the rating plate or sticker on the side of the tank, usually near the gas valve or upper access panel. On tankless units it’s on a label on the side or bottom of the cabinet.