How Old Is My Water Heater? Reliance, Rheem and Other Brands
Find your water heater's age from its serial number: Reliance, Rheem, A.O. Smith, Bradford White and more. Pick your brand, enter the serial from the rating plate, and we'll decode the manufacture date — then this lifespan calculator shows where that age sits in a typical water heater's life.
Where’s the serial number?↓
- On the rating plate — a large sticker on the side of the tank, usually in the upper half near the hot and cold water connections.
- On gas models, above or beside the gas control valve near the bottom.
- On electric models, near the upper thermostat access panel.
- If the label is faded or painted over, the same serial is often stamped into the metal jacket underneath.
Not 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.
- Rheem and Ruud put the date in the first four digits of the serial: two for the month, then two for the year. 1209D01234 is December 2009. Richmond and Vanguard tanks use the same scheme.
- A.O. Smith uses year then WEEK, not month — 1604123456 is week 4 of 2016. The same scheme covers State, American, Reliance and the Whirlpool-branded heaters sold at Lowe's, which are built by A.O. Smith and have nothing to do with the company that makes washing machines.
- Bradford White uses two letters: the first is the year, the second the month, skipping the letters I, O, Q, R, U and V. Because it only uses 20 letters, the code repeats every 20 years — so the same letter means 2007 and 1987.
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
A water heater typically lasts 8–15 years, averaging about 10.
What does the age mean if something is wrong?
Age changes the economics; symptoms tell you what to diagnose. Neither alone determines the answer.
Usually worth diagnosing/repairing
Replacement becomes more worth considering when
Still not sure? See the full repair-or-replace guide →
And the money: A repair on a water heater near or beyond its typical lifespan deserves closer comparison with replacement — and because a tank fails by leaking rather than by stopping, waiting for certainty can turn a planned replacement into an emergency call plus water damage.
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.
Where a water heater sits in its lifespan
8–15 years
Typical range
~10 years
Planning average
Early life (Years 1-5)
Thermocouples on gas models and heating elements on electric ones are examples of cheap parts that can fail — not a sign the tank is failing.
Mid-life (Years 6-9)
The anode rod is usually spent by now. Replacing it is inexpensive and is one of the best things you can do to extend the tank's life — most people never do it.
Planning window (Years 10-12)
Sediment build-up reduces efficiency and causes rumbling. Corrosion begins working on the tank itself once the anode is gone, and repair history starts to matter more than the age number alone.
Beyond typical range (Years 13+)
Past typical life. A leaking tank is a matter of when, not if, and it fails by leaking rather than by stopping — see `replaceSignals` for what that looks like before it happens.
*Actual lifespan depends on usage, maintenance and quality. Well-maintained appliances often exceed these averages.
*Actual lifespan depends on water hardness, whether the anode rod was ever replaced, and usage. A well-maintained tank often outlasts these averages.
If there’s a problem, age changes the repair economics; if it’s working, maintenance is the next step.
A tank water heater lasts 8 to 15 years, averaging about 10 — where it lands in that range comes down mostly to the anode rod, the one part inside it that almost nobody ever replaces. On a younger tank, an isolated fault (a thermocouple, a heating element) is often relatively inexpensive next to a new heater, so repairing is frequently the straightforward call.
As a tank ages past the point the anode rod would normally be spent, sediment build-up and corrosion become more relevant to the repair-vs-replace decision — and once the tank itself is corroding, no repair fixes that, only a new tank does. Repair history starts to matter as much as the age number itself.
The screening line applies with a real twist here: a water heater fails by LEAKING rather than by stopping, so waiting for a clear verdict can turn a planned replacement into an emergency call plus water damage. A repair approaching half the price of a comparable new tank installed is worth treating as a warning sign, especially past year 10 — but age, repair history and the specific failure still matter more than any single number.
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.
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.
- How we narrow it down:
- A typical water heater lifespan (8-15 years) already rules out most of the 20-year cycle for us automatically — a candidate older than about 30 years is dropped as implausible for a still-installed tank. Where we can find a dated source pinning a specific model to a narrower window, we apply the same notBefore/notAfter approach used for kitchen and laundry appliances, rather than defaulting to the newest cyclic year. See our full case log.
- 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:
- Reliance and A.O. Smith water heaters start 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
Did you find this helpful?
Know someone whose water heater is older than they think?
The Water Heater Series
- 1How Old Is My Water Heater? Reliance, Rheem and Other BrandsYou’re here — the tool above.
- 2How Long Does a Water Heater Last?Tank vs tankless, what changes as it ages, and the one cheap part that decides it.
- 3How Much Does It Cost to Replace a Water Heater?Installed cost by type, what a plumber charges, and the code add-ons that push the quote up.
- 4Should You Repair or Replace a Water Heater?The 50% rule, which faults are a cheap part, and which mean the tank is done.