How Old Is My Water Heater?
A water heater rarely warns you before it fails, and the failure usually involves a tank of water on the floor. Its age is the single best predictor of what happens next — and it is stamped into the serial number on the rating plate. Enter it below to decode the year.
Where is the serial number on a water heater?
- 1On the rating plate — a large sticker on the side of the tank, usually in the upper half near the hot and cold water connections.
- 2On gas models, above or beside the gas control valve near the bottom.
- 3On electric models, near the upper thermostat access panel.
- 4If the label is faded or painted over, the same serial is often stamped into the metal jacket underneath.
Not the number you want: the model number, which sits on the same plate and usually contains the tank capacity — a 40 or 50 for gallons. Only the serial carries the date.
Decode your serial number
Pick the manufacturer, then type the serial exactly as it appears. We'll read the manufacture date out of it.
Pick your manufacturer above and we'll show the exact serial format to look for.
Pick your manufacturer and we'll show you exactly what its serial number looks like and where to find it.
Reading the date code by brand
The decoder above reads all of these automatically. This is the reference if you want to work it out yourself, or check its answer — each maker hides the date differently, and the tank almost never has a plain printed date.
How old is my Bradford White water heater?
- Covers:
- Bradford White, Jetglas.
- What the serial looks like:
- Two letters then a run of digits — e.g. DG6322957. The first letter is the year, the second is the month.
- Reading the year:
- Bradford White reuses its 20 year letters, so the same letter means 2007 and 1987 — and, from 2024, 2004 as well. Pick the year that matches when the tank was installed.
- Don’t use:
- Not the model number, which starts with letters like M, RG or U followed by the capacity.
- Worked example:
DG6322957 → July 2007
Bradford White water heater age chart
First letter = year, second letter = month. The 20 year letters (I, O, Q, R, U and V are skipped) repeat every 20 years, so most letters give two possible years — the newer one is right unless the tank was clearly installed decades ago.
| 1st letter | Year |
|---|---|
| A | 2004 or 2024 |
| B | 2005 or 2025 |
| C | 2006 or 2026 |
| D | 1987 or 2007 |
| E | 1988 or 2008 |
| F | 1989 or 2009 |
| G | 1990 or 2010 |
| H | 1991 or 2011 |
| J | 1992 or 2012 |
| K | 1993 or 2013 |
| L | 1994 or 2014 |
| M | 1995 or 2015 |
| N | 1996 or 2016 |
| P | 1997 or 2017 |
| S | 1998 or 2018 |
| T | 1999 or 2019 |
| W | 2000 or 2020 |
| X | 2001 or 2021 |
| Y | 2002 or 2022 |
| Z | 2003 or 2023 |
| 2nd letter | 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: DG → D = 1987 or 2007, G = July. Source: Bradford White’s own serial-number date-code reference.
How old is my A.O. Smith, State or Reliance water heater?
- Covers:
- A.O. Smith, State, American, Reliance, U.S. Craftmaster, Whirlpool (water heaters — built by A.O. Smith, not the appliance company).
- What the serial looks like:
- Starts with four digits: the first two are the year, the next two are the week — e.g. 1604123456 is week 4 of 2016.
- Reading the year:
- Older A.O. Smith tanks (roughly pre-2000) used letter-based codes in a different order. If the decoded year looks wrong for your house, trust a printed date on the plate.
- Don’t use:
- Not the model number, which usually contains a dash and the capacity, like G6-S5040NVR.
- Worked example:
1604123456 → January 2016
How old is my Rheem or Ruud water heater?
- Covers:
- Rheem, Ruud, Richmond, Vanguard, Paloma, Splendid, Eco Sense.
- What the serial looks like:
- Ten characters starting with four digits, then a plant letter — e.g. 1209D01234. The first two digits are the month, the next two are the year.
- Don’t use:
- Not the model number, which starts with letters (XE, XG, PRO) and contains the tank capacity like 40 or 50.
- Worked example:
1209D01234 → December 2009
Is your water heater leaking, or are you just checking?
The age means different things depending on the answer. Pick one and we'll show you only what applies.
What the age actually means for a water heater
Signs it's time to replace rather than repair
Any one of these usually settles it on its own, whatever a repair quote says — each is the tank or its core going, not a part.
If you are replacing it, the next decision is the fuel and the type: gas vs. electric water heaters works out the running cost at your own utility rates, with a heat-pump column, and tank vs. tankless covers whether going tankless pays back.
How long a water heater lasts
10
years average
8
typical minimum
15
well maintained
*Actual lifespan depends on water hardness, whether the anode rod was ever replaced, and usage. A well-maintained tank often outlasts these averages.
What tends to fail, and when
| Age | What typically goes |
|---|---|
| Years 1-5 | Thermocouples on gas models and heating elements on electric ones. Cheap parts, and not a sign the tank is failing. |
| Years 6-9 | The anode rod is usually spent by now. Replacing it is inexpensive and is the single best thing you can do to extend the tank's life — most people never do it. |
| Years 10-12 | Sediment build-up reduces efficiency and causes rumbling. Corrosion begins working on the tank itself once the anode is gone. |
| Years 13+ | Past typical life. Tank failure is a matter of when, not if, and it fails by leaking rather than by stopping. |
Things worth knowing about your water heater
It fails by leaking, not by stopping
Most appliances announce the end by refusing to work. A water heater usually announces it by emptying 40 or 50 gallons onto the floor. That asymmetry is why age matters more here than for anything else in the house — the cost of being late is a flooded room, not a cold shower.
The anode rod is the part nobody replaces
A sacrificial metal rod inside the tank corrodes so the steel tank does not. It is typically spent within about five years, and replacing it costs a fraction of a new heater. Almost nobody does it, which is the main reason tanks fail around year 10 rather than lasting far longer.
Hard water shortens everything
Mineral-heavy water leaves sediment that insulates the burner from the water, making the heater work harder and run hotter. In hard-water areas the same tank can reach the end of its life several years earlier than the averages suggest.
Common questions
How old is my water heater?
Find the serial number on the rating plate on the side of the tank and enter it above. Rheem and Ruud encode the month and year in the first four digits, A.O. Smith uses the year and week, and Bradford White uses two letters for the year and month.
Where is the serial number on a water heater?
On the rating plate stuck to the side of the tank, usually in the upper half near the water connections. On gas models it may sit near the gas control valve instead. Do not use the model number — only the serial carries the date.
How long does a water heater last?
A conventional tank water heater lasts 8 to 15 years, averaging about 10. Tankless units often last 20 or more. Water hardness and whether the anode rod was ever replaced matter more than the brand.
Should I replace a water heater before it fails?
Past about 10 to 12 years, generally yes. Water heaters usually fail by leaking rather than by stopping, so waiting turns a planned replacement into an emergency call plus water damage. Replacing on your own schedule is almost always cheaper.
Protect your home appliances before they break
A home warranty covers breakdowns on your working home appliances — the kitchen and laundry machines you use every day, plus the systems that run the house.
- Not the same as home insurance
- Insurance covers disasters and theft. A home warranty covers breakdowns from normal wear and tear — the washer that simply stops working.
- One plan, the whole house
- Coverage spans the appliances and the systems together rather than a single machine, so it is bought per home, not per unit.
- Arranged before a breakdown
- Plans cover appliances that are working when you sign up, and an inspection usually is not needed. That is simply how the product works — it is bought ahead of a failure, not after one.
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