Water heater age by serial number: free finder
Check water heater age in one step: pick the brand, type the serial number from the rating plate and see when the tank was built. Six brands are covered, from Bradford White to Rheem.
How old is my water heater?
Choose the brand, then copy the serial number exactly as printed on the rating plate, letters included.
Results are estimates of the manufacture date. The rating plate and the manufacturer’s support line are the authority.
How to find the water heater age by serial number
Water heater age by serial number starts at the rating plate. On a tank water heater it is a label on the side of the tank, with the model, serial and capacity. Take a photo of it. You will want the model number later, and some plates also print a manufacture date.
Copy the serial number, not the model. Include every letter and leave out spaces if you like, because the tool ignores spaces and dashes. Then pick the brand. The date is a manufacture date. The heater was probably installed a few months after that, so the real age in the unit is a little younger than the tool says.
If the plate prints “MFG. DATE”, trust that over the serial.
Water heater serial number lookup: six brands and how they write the date
Use this water heater serial number lookup table to find your brand. Each brand has its own page with a worked example and a list of what the tool cannot read. The examples come from documented serials.
| Brand | How the date is written | Example | Tool reads it as |
|---|---|---|---|
| Bradford White | Two letters: year, then month. Year letter repeats every 20 years. | DG6322957 | July 2007, possibly 1987 |
| A. O. Smith | Year, then week. Older tanks use letters. | 1719106145074 | Week 19 of 2017 |
| State | Same as A. O. Smith, which owns the brand. | 1735107397129 | Week 35 of 2017 |
| Rheem and Ruud | Month, then year, after a letter prefix. | RH 0806B17262 | August 2006 |
| GE | Month, then year, on Rheem-era tanks. | PC 0806203893 | August 2006 |
| Whirlpool | Year, then week. | 0128104380 | Week 28 of 2001 |
Bradford White’s year letters repeat, so its date is the least certain. Check the ANSI date on the plate.
Brands that share a code
Several names on a water heater are not separate manufacturers. State is an A. O. Smith brand, so the two share a code. InterNACHI lists Whirlpool-branded water heaters under American Water Heaters, an A. O. Smith company, and gives them the same year-and-week rule.
GE-branded tank water heaters have been built by Rheem, according to the Building Intelligence Center, and InspectApedia names the Rheem-built GE series. They use the Rheem month-and-year layout. These links come from third-party references, not from the manufacturers, so the GE and Whirlpool rules are rated lower in our research than Bradford White or A. O. Smith.
How long should the water heater last?
The tool measures age against a typical life of 12 years. Published numbers vary. The NAHB study lists 10 years for a gas tank and 11 for an electric one. Rheem gives 8 to 12 years for a conventional tank. The Department of Energy puts storage tank water heaters at 10 to 15 years.
So a 12-year-old heater is not automatically due. It is at the point where you should look closer: leaks at the base, rust-colored water, a rumbling tank or a rising repair history. Our water heater lifespan guide covers the signs and how to plan replacements across a portfolio.
What the tool cannot read
The rules were researched for tank water heaters. They miss some units:
- Bradford White tankless and Aero-built oil-fired units use other formats
- Newer GE-branded heat pump models may use a different code
- Rheem serials that put a week of 13 or higher where the month goes
- Very old A. O. Smith and State serials in styles we could not confirm
When the tool cannot date a serial, it says so. A wrong answer is worse than no answer when you are budgeting a replacement.
Put the age on the unit's record
A one-off answer is easy to lose. In Invendoory, a water heater is an item in the unit’s inventory with its type (gas, electric, tankless or heat pump), gallons, whether it is strapped, serial, install date and expected life. You can tag a photo of the serial plate to it, and a life-used bar shows how much of its life is gone.
That lets a supervisor sort a portfolio by water heaters closest to the end of their life instead of waiting for a leak. See the asset inventory for how items are recorded, or the Appliance Age Finder for other equipment.
Water heater age questions
How do I find a water heater's age by serial number?
Find the rating plate on the side of the tank, copy the serial and choose the brand in the tool. It reads the date characters and returns a manufacture date, the age in years and the share of a typical life used. Confirm against any manufacture date printed on the plate.
Where is the serial number on a water heater?
It is on the rating plate, a label on the side of the tank. The plate also shows the model number, capacity and fuel type. Take a photo so you can copy the serial exactly, because one wrong letter changes the date.
Why does the tool show two years for Bradford White?
Bradford White repeats its year letters every 20 years, so a D can mean 1987 or 2007. The tool shows the most recent year first and lists older ones. The ANSI standard date on the plate shows which is right.
Is a 12-year-old water heater due for replacement?
Not necessarily. Published lifespans run from about 8 to 15 years for a tank. At 12 years, inspect it for leaks, corrosion and repair history, and compare the repair cost against replacement before deciding.
Does this work for tankless water heaters?
The rules were researched for tank units. Bradford White tankless units use other formats that the tool does not read. For tankless units, check the plate for a printed date and ask the manufacturer’s support, since published tankless life is 20 years or more.
Sources
- Bradford White For The Pro – Determining the Age of a Water Heater
- Bradford White FAQ – How to read the serial number date code chart
- Building Intelligence Center – Bradford White water heater age
- InterNACHI Water Heater Dating Chart
- A. O. Smith Service and Warranty Guide, July 2024 (How to Read the Serial Number)
- Building Intelligence Center – A. O. Smith water heater age
- Building Intelligence Center – State water heater age
- Building Intelligence Center – Rheem water heater age
- InspectApedia – Rheem water heater age decoder
- Building Intelligence Center – GE water heater age
- InspectApedia – Hotpoint and GE water heater age
- Building Intelligence Center – Whirlpool water heater age
- InterNACHI forum – Whirlpool serial 0128104380
- NAHB and Bank of America Home Equity, Study of Life Expectancy of Home Components (2007)
- U.S. Department of Energy, Energy Saver Guide (2022)
- Rheem, Water Heater Lifespan: When to Repair vs. Replace
Checked October 2026.
Keep the water heater age on file
Invendoory records the serial, install date and life used for every water heater in every unit. Open the live demo, no signup needed.