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How Old Is My Water Heater? A Complete Guide For Popular Models

How Old Is My Water Heater? A Complete Guide For Popular Models

That’s a question I heard a lot when I was managing properties.

That’s why I decided to explain more about how to tell a water heater’s age.

How to Determine the Age of Your Water Heater

An image of a water heater in a utility room next to other household appliances


Water heaters can last a long time. But the expected lifetime of a water heater varies considerably. Some models can provide faithful service for up to 20 years. However, others may only last around eight years.

It partly depends on whether the heater uses electricity or gas as the fuel source. The specific unit also has an effect. Some manufacturers and models tend to last longer, sometimes a lot longer.

The amount of hot water you use also has a major impact on heater life. Finally, the mineral content of the water also affects it. A higher mineral content means a shorter-lived heater.

With all this in mind, if you have a standard electric water heater, you can normally expect it to be in good shape for 10 to 15 years.

Of course, that’s plenty long enough to lose the original sales receipt for the heater as well as the warranty and other information.

Unless you keep good records, you likely can’t recall exactly when you acquired your water heater.

If the heater was already installed in a property when you moved in, it’s even less likely that you’ll know when the heater was manufactured, purchased, and installed.

Why Heater Age Matters

Lady taking a cold shower because she didn't ask "how old is my water heater" and crossing her arms while shivering and closing her eyes


When water heaters go bad, they can go really bad. Running out of hot water in the middle of a shower is the least of it.

A worn-out water heater can also leak, put out water that’s too hot or too cold, reduce your water flow to a trickle, or cause water to smell or look bad.

In the worst case, a heater can literally explode. Water damage from a ruptured heater can easily cost thousands to repair.

Warning signs like little or no hot water, low flow, and leaking fittings can alert you to the fact that your water heater is reaching the end of its useful life. This can help you decide whether to try to repair or replace the heater.

A timely replacement of a water heater that’s about to fail can save lots of time, money, and energy compared to waiting for it to go.

And one of the best ways to determine whether your heater is soon to become a problem is to know how old it is. But how do you do that?

As it turns out, the answer gets a little complicated. But if you use the following information, you can reliably tell how old your water heater is and, hopefully, replace it before trouble starts.

Determining Water Heater Age

All water heaters have information on them that you can use to see how old the heater is. Ideally, you can simply look at the manufacturer’s label. This should be on the side of the unit.

It will usually include the date the heater was installed. However, sometimes the installation date may not appear there. Labels get torn and even completely fall off.

If that happens, you can still see how old your heater is by using the serial number. The heater’s serial number is imprinted on the heater at the factory, so it should always be there.

The problem with this approach is that there are a lot of heater manufacturers. And every manufacturer has its own way of identifying a heater’s age.

If you approach the problem as if it were a puzzle or a code to break, you can still get the information you need. You just need the brand name of the heater and the serial number.

Here’s a guide to help you find the heater age information for the most popular brands of water heaters.

Decoding Heater Serial Numbers

Image of an appliance repair man wearing a navy cap and holding a clipboard for a piece on how old is your water heater

Alpa Prod/Shutterstock

A water heater’s serial number typically uses four digits to indicate the heater’s age. The serial number often has several more digits in it. But these other digits usually don’t have anything to do with age. You can ignore these.

Most of the time, the heater age is given first in the serial number. But it’s often not anything as simple as “December 31, 2010” or even “12/31/2010.”

Instead, each heater maker uses a code. To figure out your heater age, you just have to know the code.

Rheem and Ruud

The first four numbers in the serial number give the two-digit month and the two-digit year the heater was manufactured. For instance, 1215 means the heater was made in December 2015.

AO Smith

For heaters made after 2008, the first two digits of the serial number give the year, and the next two digits give the week of manufacture. So 1208 means it was made in the eighth week of 2012.

For older heaters, the second letter in the serial number gives the month. A is for January, B is for February, and so on, all the way to M is for December. The third and fourth numbers give the year.

Bradford White

This maker uses the first two digits of the serial code to give the age. The first letter gives the year. A is 2004, B is 2005 or 1985, C is 2006 or 1986, D is 2007 or 1987, and E is 2008 or 1998.

F is 2009 or 1989, G is 2010 or 1990, H is 2011 or 1991, J is 2012 or 1992, K is 2013 or 1993, L is 2014 or 1994, M is 2015 or 1995, N is 1006 or 2016, P is 1997 or 2017, and S is 1998 or 2018.

T is 1999 or 2019, W is 2000 or 2020, X is 2001 or 2021, Y is 2002 or 2022, and Z is 2003 or 2023. Letters I, O, Q, R, U, and V aren’t used. The second letter gives the month. A is for January.

B is for February. C is for March. D is for April. E is for May. F is for June. G is for July. H is for August. J is for September. K is for October. L is for November. M is for December. Letters I and N aren’t used.

Getting Age of Other Heaters

These three manufacturers make the most popular heater brands in the United States. Many different brands may come from the same manufacturer.

For example, A.O. Smith makes heaters sold under the Tru Value, Ace, and Whirlpool brands, among many others.

In addition to the familiar Rheem and Ruud brands, Rheem has made heaters sold under the General Electric, Hotpoint, and Western Auto labels.

And there are actually quite a few other water heater manufacturers, although you are less likely to have one of these other brands. 

If your heater isn’t made by one of the three big manufacturers, you can still get the information you need to see how old your heater is.

To get a complete list of water heater makers, along with the brands they’ve supplied and the key to decoding heater age, check the website of the National Association of Certified Home Inspectors.

This is the most complete and up-to-date list of water heater makers, brands, and manufacture date codes around.

How To Check Your Water Heater Age

A water heater element that's crusted over because someone didn't know how to check the age of their water heater


To summarize, knowing the age of your water heater can help you decide whether you should replace it now or wait for something to go wrong.

When you see signs of age, such as running out of hot water, it can mean the tank has gotten filled up with sediment or something else is about to go wrong.

If you know your heater is about to reach the end of its useful life, replacing it before it fails can save you a lot of time, energy, and money.