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Water Heater Age Calculator: How Old Is My Water Heater?
Type in the serial number from the label on the tank. You’ll get the build date, the age today and how much of a typical life is left, then whether a repair still makes sense.
- Decodes Bradford White, A.O. Smith and Rheem serials
- Typical lifespans for gas, electric and tankless
- Built-in 50 percent repair test
- Any brand works with an install year
Date rules from Bradford White and City of Palo Alto Utilities. Lifespans from NAHB. Cost rule from Consumer Reports.
What kind of water heater is it?
It sets the typical lifespan we compare against.
Which brand is on the label?
We only decode serials where a published rule exists. Any other brand, you enter the year.
Built
Have a repair quote? Run the 50 percent test
The basics
How old is my water heater?
The build date is coded into the serial number on the label on the side of the tank, and each brand codes it its own way. Bradford White publishes its letter chart. City of Palo Alto Utilities publishes the rules for A.O. Smith and Rheem. For any other brand, the label, your paperwork or the manufacturer’s support line is the reliable route.
I’d date the tank before anyone quotes a repair on it, because a 3-year-old heater and a 13-year-old one with the same leak are two different decisions.
Brand by brand
How the calculator reads each brand
Only brands with a published rule get a serial lookup. Here’s what each source says, and where the calculator stops.
Bradford White
Bradford White’s My Water Heater page says the first two characters of the serial are the year and month of manufacture. Both are letters, and the charts below are the maker’s own.
Each year letter stands for two years, 20 apart. From D onward the later year hasn’t happened yet, so there’s one answer. A, B and C (2004 or 2024, 2005 or 2025, 2006 or 2026) need you to pick.
HK= October 2011 (Palo Alto’s example, HK16433183)A.O. Smith
Palo Alto’s water heater age guide gives two A.O. Smith formats. Current serials start with four digits: the year, then the week of manufacture.
Serials made before 2008 use a month letter in the second position, A for January and so on, skipping I, followed by a two-digit year.
2037= week 37 of 2020, early September (Palo Alto’s example)2C06= March 2006 (pre-2008 format, Palo Alto’s example)Rheem
The same Palo Alto guide reads Rheem serials as month then year: the first two digits are the month and the next two are the year.
Some Rheem serials start with letters instead of four digits. The published rule doesn’t cover those, so the calculator asks for the year rather than guessing.
1209= December 2009 (Palo Alto’s example, 1209D01234)Ruud, State, American and others
We didn’t find a date rule published by the maker or a utility for Ruud, State, American, Richmond or the store brands. Palo Alto’s advice for any brand it doesn’t list is to visit that manufacturer’s website.
Before you call, read the whole label: some print a manufacture date outright. An installer’s sticker or your receipt gives an install date, which is close enough for the calculator.
Bradford White year letters (1st character)
Bradford White doesn’t use I, O, Q, R, U or V for years.
| Letter | Year | Letter | Year |
|---|---|---|---|
| A | 2004 or 2024 | L | 2014 |
| B | 2005 or 2025 | M | 2015 |
| C | 2006 or 2026 | N | 2016 |
| D | 2007 | P | 2017 |
| E | 2008 | S | 2018 |
| F | 2009 | T | 2019 |
| G | 2010 | W | 2020 |
| H | 2011 | X | 2021 |
| J | 2012 | Y | 2022 |
| K | 2013 | Z | 2023 |
Bradford White month letters (2nd character)
Bradford White doesn’t use I or N through Z for months.
| Letter | Month | Letter | Month |
|---|---|---|---|
| A | January | G | July |
| B | February | H | August |
| C | March | J | September |
| D | April | K | October |
| E | May | L | November |
| F | June | M | December |
Later years in each pair (2027 for D up to 2043 for Z) are from Bradford White’s chart too. The calculator hides them until they’ve happened.
Lifespans
How long do water heaters last?
The lifespans in the calculator come from the NAHB / Bank of America Home Equity Study of Life Expectancy of Home Components (February 2007). Its appliance table puts an electric tank at 11 years and a gas tank at 10. Its plumbing section says tankless water heaters last more than 20 years. The figures are based on first-owner use.
City of Palo Alto Utilities uses the same line for gas: if your gas water heater is more than 10 years old, it may be time to replace it.
Owners on r/Plumbing say the water itself shifts those numbers. These are reports, not measurements:
“Water quality has a massive effect on life span. Manufacturers typically state 8-12 year life expectancy.”
Reply on r/Plumbing, March 2026, from someone with soft water who says 15 to 20 years is normal where they live
The decision
Repair or replace the water heater?
Consumer Reports’ rule is about money. Enter your quote and the installed price of a new heater, and the calculator runs the test. Age tells you how hard to apply it, so the calculator puts every heater in one of three bands. The bands are our rule of thumb.
“No matter who does the repair, don’t spend more than 50 percent of the cost of a new product on repairing an old one.”
Consumer Reports, January 9, 2014
It hasn’t reached half its typical life. Fix the cause and keep it running.
If the quote is more than half the price of a new one, replace it.
It may keep going, but price a replacement alongside any repair.
“Water Heater age? Repairable?”
“If it’s never been flushed or had an anode rod replacement that tank will most likely rust through sometime in the next few years and start leaking.”
Reply to an owner with a 2007 heater and a rust-colored leak, r/Plumbing, July 2026“It was manufactured the 10th week of 2007. It’s most likely out of warranty.”
Another reply in the same thread
Why an old repair gets harder
“Water heater repairs are easy in concept until you’re actually trying to remove a 19 year old anode rod with a breaker bar”
Reply in the same r/Plumbing thread
Repairing other appliances too? Our appliance age calculator dates GE, Bosch and LG serials and runs the same test.
Find the tag
Where’s the serial number on a water heater?
It’s on the rating label stuck to the side of the tank. Palo Alto describes it as the label with the manufacturer’s name, model, serial number and other technical specifications. Bradford White calls it the rating plate.
Reading the label
- Find the serial, not the model. Both sit on the same label. The model number describes the heater. The serial is the one that carries the date.
- Photograph it with the flash on. Water heaters live in closets and garages, and a photo you can zoom is easier than reading it with your head against the tank.
- Read the first four characters carefully. Those are the ones the calculator uses. On a Bradford White a letter O and a zero look alike, but O isn’t on either chart.
- Check for a printed date. Read the whole label before decoding. If a manufacture date is printed on it, that beats any formula.
Label worn off or unreadable?
- Look for an installer’s sticker on the tank or the pipes, and check it for an install date.
- Check your paperwork. A receipt or invoice gives the install date, which works in the calculator.
- Ask the manufacturer. Palo Alto’s advice for brands it doesn’t list is the maker’s website. Have the model and serial number ready when you contact them.
- Post a photo to r/Plumbing. Owners there regularly decode labels for each other, as in the A.O. Smith thread below.
“Anyone help me decode the age of my water heater? A.O. Smith”
“January of 2001”
Top reply on r/Plumbing, September 2026“Go to we bsite enter serial number. Ez peazy.”
Another reply in the same thread
Renters
Renting? Show your landlord how old it is
Two of the 2026 “water heater age” threads we read on r/Plumbing came from tenants who wanted the age before asking for a replacement. A date with its source is harder to wave away than “it looks old”.
What to send
- A photo of the label with the serial number readable.
- The decoded date and where the rule comes from, for example Bradford White’s own chart or Palo Alto’s guide for A.O. Smith and Rheem. Link this page if it helps.
- What’s wrong, with dates. Leaks, rust-colored water, a valve that’s been replaced, no hot water. A photo of any leak.
- Put it in writing (email or your building’s portal), so there’s a record of when you reported it.
What the threads show
- One tenant wanted the age to back up a replacement request to property management for a tank in “pretty rough shape”.
- Another had just moved in, had a plumber replace a leaking pressure valve, and wanted to confirm the age before telling the landlord. Replies disagreed on the exact date (July 2006 or early 2007) but agreed it was about 19 years old.
- Labels mislead: in that second thread one reply pointed out a Whirlpool sticker and a Craftmaster label on a heater it identified as an A.O. Smith.
“I’m sure knowing the age would help me when I request a replacement from property management.”
Tenant on r/Plumbing, March 2026
“I want to confirm the age before letting my landlord know”
New tenant on r/Plumbing, April 2026
Who pays for a replacement depends on your lease and local law, which this page can’t tell you. The age is the fact you can bring to that conversation.
Before you pay
Two checks before you pay for a repair
Once you know the age, these can turn a paid repair into a covered one. Each needs only the model and serial number.
Is it still under warranty?
Bradford White’s My Water Heater page has a warranty lookup: you enter the serial number and it returns your warranty information. The same page links to warranty registration.
For other brands, have the model, serial and install date ready when you call. Terms vary by brand and model, so read the warranty for yours.
Source: Bradford White My Water Heater page, checked October 25, 2026.
Has it been recalled?
Search the brand and model at cpsc.gov/Recalls. The US Consumer Product Safety Commission says recall remedies typically consist of a refund, repair or replacement, and that you should typically stop using a recalled product and follow the recall notice.
The CPSC also takes reports of unsafe products at SaferProducts.gov.
Source: CPSC FAQ and recall search, checked October 25, 2026.
FAQ
Water heater age questions
How do I read a Bradford White serial number?
Bradford White says the first two characters are the year and month of manufacture. The first letter is the year (from its chart: H is 2011, X is 2021) and the second is the month (A is January, M is December). HK means October 2011.
How do I tell the age of an A.O. Smith water heater?
On current serials the first two digits are the year and the next two are the week, so 2037 is week 37 of 2020. On serials made before 2008, the second character is a month letter and the next two digits are the year, so 2C06 is March 2006. Both rules are from Palo Alto’s water heater age guide.
How do I tell the age of a Rheem water heater?
When the serial starts with four digits, the first two are the month and the next two the year, so 1209 is December 2009. If your Rheem serial starts with letters, that rule doesn’t cover it. Check the label for a printed date or ask Rheem.
Should I replace a water heater just because it’s old?
Not because of the age alone. Palo Alto says a gas heater more than 10 years old may be due for replacement, and NAHB puts typical tank life at 10 to 11 years. If it’s running fine, the age tells you to budget for a replacement and to act quickly on any leak.
Why does the calculator show two years for my Bradford White?
Bradford White reuses each year letter after 20 years. For A, B and C both years have now happened: 2004 or 2024, 2005 or 2025, 2006 or 2026. Pick the one that fits when the heater went in.
Last checked October 25, 2026. Date rules come from Bradford White’s own page and City of Palo Alto Utilities’ guide. When another maker publishes its rule, we’ll add it.
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