How to Tell the Age of Your Water Heater (Rheem, A.O. Smith & Bradford White)
Where to find the serial number, how the major brands encode the manufacture date, and what your heater’s age means for repair or replacement.
In this guide
Your water heater’s age is usually hidden in the serial number on the rating label on the side of the tank. Bradford White uses a letter for the year and a letter for the month at the start of the serial number. Newer A.O. Smith and State heaters typically start with four digits for the year and week. Many Rheem and Ruud heaters show the month and year as four digits near the start of the serial number. Some newer labels simply print the manufacture date.
Knowing how old your water heater is helps you decide whether a repair is worth it and when to start planning a replacement. Most tank water heaters last around 8 to 12 years, but you can’t judge age by looks alone. The good news is that the date is almost always on the heater, if you know how to read it.
Where to find the serial number
Look for the rating label, a sticker on the side of the tank, usually near the gas control or the upper access panel. It lists the model number, serial number, capacity, fuel type and ratings. Use a flashlight; labels in closets and basements can be faded. Some newer labels print the manufacture date directly, which saves you from decoding anything.
Bradford White
Bradford White serial numbers start with two letters. The first letter is the year and the second is the month. The year letters repeat on a 20-year cycle and skip I, O, Q, R, U and V, so you need to use common sense about which cycle your heater falls in.
| Year letter | Year | 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 |
Month letters: A = Jan, B = Feb, C = Mar, D = Apr, E = May, F = Jun, G = Jul, H = Aug, J = Sep, K = Oct, L = Nov, M = Dec. For example, a serial number starting with “TC” would indicate March 2019. Earlier cycles used the same letters (A was also 1984), which is why the heater’s condition matters too. If you’re unsure, Bradford White’s own resources or a plumber can confirm.
A.O. Smith and State
On newer A.O. Smith and State water heaters, the serial number typically begins with four digits: the first two are the year and the next two are the week of the year. For example, a serial starting with “1825” would indicate the 25th week of 2018. Older models used different formats, so if the first digits don’t make sense as a year, check the manufacturer’s guidance.
Rheem, Ruud and Richmond
On many Rheem-built heaters (including Ruud and Richmond), the month and year appear as four digits near the start of the serial number, after any leading letters: the first two digits are the month and the next two are the year. For example, “0517” would indicate May 2017. Formats have changed over the years, so treat this as a guide and confirm with Rheem if the result doesn’t look right.
Other ways to find the age
- A printed manufacture date on newer labels.
- An installation or inspection tag on the heater or nearby pipes.
- Your home inspection report or closing documents.
- Permit records for the most recent water heater replacement.
- Ask a plumber. We decode serial numbers every day and can usually tell you the age in a minute.
What your water heater’s age means
| Age (tank heater) | What it usually means |
|---|---|
| Under 6 years | Repairs are usually worth it. Keep up with annual flushing. |
| 6 to 10 years | Repairs often still make sense. Have the anode rod checked. |
| 10+ years | Start planning a replacement, especially if you see rust, leaks or rumbling. |
For the warning signs to watch for, read how long water heaters last. If you’re deciding whether to repair or replace, what affects the cost of replacing a water heater explains what a complete replacement should include.
Not sure how old yours is?
Can’t read your label or not sure what the serial number means? Send us a photo or call, and we’ll tell you how old your heater is and whether it’s worth repairing.
Key takeaways
- The manufacture date is usually encoded in the serial number on the rating label.
- Bradford White uses a year letter and a month letter at the start of the serial number.
- Newer A.O. Smith and State serials usually start with the year and week.
- Many Rheem-built heaters show the month and year as four digits near the start.
- Tank heaters past about 10 years are good candidates for planned replacement.
Frequently asked questions
Where is the serial number on a water heater?
On the rating label, a sticker on the side of the tank, usually near the gas control or upper access panel.
How do I read a Bradford White serial number?
The first letter is the year and the second letter is the month. For example, “TC” indicates March 2019. The year letters repeat every 20 years.
How do I tell the age of an A.O. Smith water heater?
On newer models, the first four digits of the serial number are the year and week. For example, 1825 means the 25th week of 2018.
How old is too old for a water heater?
Most tank water heaters last about 8 to 12 years. Past 10 years, it’s smart to plan a replacement, especially if you see rust, leaks or rumbling.
Does the age matter if my water heater still works?
Yes. Older tanks are more likely to leak, and replacing one on your schedule is easier than after it fails and floods the area around it.
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