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How old is your water heater?

Enter the serial number from your tank’s data plate to find its water heater age and exact manufacture date — free, instant, no sign-up.

The answer is usually stamped right into your tank: the serial number on the rating plate (the silver sticker on the side) encodes the manufacture date for virtually every brand — Rheem and A.O. Smith units use digits, Bradford White uses a letter code, and tankless brands like Navien and Rinnai hide the date in the first few characters. Decode it above, or browse every brand’s format on the age chart.

1. Choose your brand

How it works

1

Find the rating plate

Look for the silver sticker on the side of the tank — it lists the model and serial numbers. It’s usually at eye level, and no photo or tools are needed.

2

Enter the serial number

Type the serial exactly as printed. Letters matter, and the serial is not the same as the model number.

3

Get the manufacture date

The decoder shows the year and month your unit was built, plus how that age compares to a typical 8–12 year tank lifespan.

What does the rating plate look like?

Tankless water heater mounted on a wall above a sink — the serial number is on the rating plate sticker on the side panel

Every water heater carries a rating plate (data plate) — a silver or white sticker that lists the model number, serial number, and capacity together. On tank units it’s usually on the upper half of the side of the tank, near eye level. On tankless units it’s on the side panel or behind the front cover.

The model number describes the product line. The serial number is unique to your unit — and it’s the one that encodes the manufacture date. Don’t confuse the two: enter the serial, not the model, in the lookup above.

Sticker faded or painted over? Photograph it and bump the contrast — most dates only need the first four characters of the serial to decode. Every brand’s exact format is on the water heater age chart, with worked examples.

Look up by manufacturer

RheemAlso covers Ruud, Richmond, Marathon, and GE-branded water heaters built by Rheem.Decode a Rheem serial →A.O. SmithAlso covers State, Reliance, American, U.S. Craftmaster, and Kenmore units built by A.O. Smith.Decode a A.O. Smith serial →Bradford WhiteDecode the letter-based Bradford White serial format — including its 20-year repeat cycle.Decode a Bradford White serial →NavienTankless. Decode the Navien serial date code on the data plate.Decode a Navien serial →RinnaiTankless. Find the manufacture date in a Rinnai serial number.Decode a Rinnai serial →BoschTankless. Decode Bosch water heater serial numbers.Decode a Bosch serial →

Look up by store brand

AmericanMade by A.O. Smith — same serial format.Decode a American serial →ApolloMade by A.O. Smith — same serial format.Decode a Apollo serial →Aqua ThermMade by Rheem — same serial format.Decode a Aqua Therm serial →CimarronMade by Rheem — same serial format.Decode a Cimarron serial →Coast to CoastMade by Rheem — same serial format.Decode a Coast to Coast serial →U.S. CraftmasterMade by A.O. Smith — same serial format.Decode a U.S. Craftmaster serial →Energy MasterMade by Rheem — same serial format.Decode a Energy Master serial →EnvirotempMade by A.O. Smith — same serial format.Decode a Envirotemp serial →EverkleenMade by Rheem — same serial format.Decode a Everkleen serial →GEMade by Rheem — same serial format.Decode a GE serial →GSWMade by A.O. Smith — same serial format.Decode a GSW serial →HotpointMade by Rheem — same serial format.Decode a Hotpoint serial →InterthermMade by Rheem — same serial format.Decode a Intertherm serial →John WoodMade by A.O. Smith — same serial format.Decode a John Wood serial →KenmoreMade by A.O. Smith — same serial format.Decode a Kenmore serial →MainstreamMade by Rheem — same serial format.Decode a Mainstream serial →MaytagMade by A.O. Smith — same serial format.Decode a Maytag serial →MillerMade by Rheem — same serial format.Decode a Miller serial →Montgomery WardMade by Rheem — same serial format.Decode a Montgomery Ward serial →PrestigeMade by A.O. Smith — same serial format.Decode a Prestige serial →Rheem ProfessionalMade by Rheem — same serial format.Decode a Rheem Professional serial →QuakerMade by A.O. Smith — same serial format.Decode a Quaker serial →RelianceMade by A.O. Smith — same serial format.Decode a Reliance serial →RevereMade by A.O. Smith — same serial format.Decode a Revere serial →RichmondMade by Rheem — same serial format.Decode a Richmond serial →RuudMade by Rheem — same serial format.Decode a Ruud serial →StateMade by A.O. Smith — same serial format.Decode a State serial →True ValueMade by A.O. Smith — same serial format.Decode a True Value serial →VanguardMade by Rheem — same serial format.Decode a Vanguard serial →WeatherKingMade by Rheem — same serial format.Decode a WeatherKing serial →WhirlpoolMade by A.O. Smith — same serial format.Decode a Whirlpool serial →

Guides

Water heater age chartSerial-format cheat sheet for every major brand on one page.Read the guide →How long do water heaters last?Typical service life by brand, tank vs. tankless.Read the guide →Tankless vs tank water heaterLifespan, energy, and cost — which fits your home?Read the guide →Signs your water heater is about to failRust-colored water, rumbling, leaks — when to replace, not repair.Read the guide →Water heater warranty lookupHow warranty terms map to your serial number, brand by brand.Read the guide →

Tools

Serial format detectorPaste any serial — find out which brand format it uses and decode it.Use the tool →Photo lookupCan't read the sticker? Upload a photo and read the serial off it.Use the tool →

Why water heater age matters

Water heater pipes and pressure gauges in a home utility room

Plan for replacement

Tank water heaters typically last 8–12 years. Knowing the manufacture date tells you whether to budget for a replacement now or later — before a leak forces an emergency purchase.

Avoid water damage

Most tanks fail by leaking or bursting. Replacing an aging unit on your schedule is far cheaper than repairing a flooded garage, closet, or basement.

Check warranty coverage

Warranties run from the manufacture date, not the install date. The serial number is the only reliable way to know when the clock started.

Buying or selling a home

Home inspectors flag water heaters near the end of their life. Decode the serial to negotiate from facts instead of guesses.

Common questions

How old is my water heater?

The fastest way to find out is the serial number on the rating plate. Enter it in the lookup above and you’ll get the exact manufacture date. Most brands encode the year and month directly in the serial — no receipt, installer, or guesswork required.

How can I tell the age of a water heater?

The fastest way is the serial number on the rating plate — most brands encode the year and month (or week) directly in the first few characters. Rheem-built units (Ruud, Richmond, GE) use month + year digits; A.O. Smith-built units (State, Reliance, American) use year + week digits; Bradford White uses a letter code; and tankless brands like Navien, Rinnai, and Bosch hide the date in the serial too. If the sticker is gone, the age can only be estimated from the model line and the unit’s condition — the serial is the only reliable method, which is why this site exists.

Do home inspectors check water heater age?

Yes. Water heater age is a standard line item on home inspection reports: inspectors read the manufacture date off the rating plate serial number and flag tanks past the typical 8–12 year lifespan as near-term replacement candidates. If you are buying or selling, decode the serial yourself before the inspection so you negotiate from facts — the free lookup above does it in seconds.

Where is the serial number on a water heater?

On the rating plate — the silver or white sticker on the upper half of the tank jacket, usually near eye level. It lists the model number, serial number, and capacity together. Don’t confuse the serial with the model number: the date code lives in the serial. On tankless units, look for the data plate on the side or underside of the cabinet.

How long do water heaters last?

Tank water heaters typically last 8–12 years, depending on water quality and maintenance. Tankless units generally last longer because there’s no storage tank to corrode. If your decoded date puts a tank past 10 years, it’s smart to plan a replacement before a leak decides for you.

Can I tell the age from the model number?

No. The model number describes the product line — capacity, fuel type, and feature tier — not when the unit was built. The manufacture date is encoded in the serial number, which is unique to your unit. That’s why the lookup asks for the serial, not the model.

Why does a Bradford White serial give two possible years?

Bradford White uses a single letter for the year, and those letters repeat on a 20-year cycle — so the same letter can mean 2004 or 2024. There’s no digit that separates the cycles, so our decoder lists every plausible year instead of guessing. The unit’s condition and installation date usually make the right cycle obvious.

What if my serial isn’t recognized?

Double-check the serial against the rating plate — it’s easy to transpose a character or copy the model number by mistake. If it still doesn’t decode, your unit may use an older or regional format; try the brand-specific lookup pages linked above, which show example serials for each manufacturer. We never guess a date we can’t back up.