Water heater age by serial number
Choose tank or tankless, pick the brand and type the serial number from the rating label. We'll decode the manufacture date and compare the age with the typical lifespan.
Serial number age lookup
Choose your brand
Each brand page explains where the label is, how that brand's code works, with worked examples, and what the result means for that heater.
- A. O. Smith Year (2 digits) + week (2 digits) (2008–present)
- American Water Heater Decoder available in the tool
- Bradford White Year letter + month letter + 8 digits (December 2007–present)
- GE Decoder available in the tool
- Kenmore Decoder available in the tool
- Navien Decoder available in the tool
- Noritz Decoder available in the tool
- Reliance Same code as A. O. Smith
- Rheem Month (2 digits) + year (2 digits) + plant letter + 5 digits
- Richmond Same code as Rheem
- Rinnai Decoder available in the tool
- Ruud Same code as Rheem
- State Same code as A. O. Smith
- Whirlpool Decoder available in the tool
Where to find the serial number on a water heater
The rating label is on the side of the tank. On gas models it's usually just above the gas control valve; on electric models, between the two heating-element covers. Tankless units have the label on the side of the cabinet. Read the line marked Serial or S/N, not the model number. If the label prints MFG DATE, that's the answer without any decoding.
Our step-by-step guide, how to tell the age of a water heater, includes a diagram of label locations and what to do if the label is missing.
How long water heaters last
| Equipment | Typical life |
|---|---|
| Water heater (tank) | 8–12 years |
| Water heater (tankless) | 15–20 years |
Gas tanks tend toward the lower end of the range and electric tanks toward the upper end. Hard water, an unflushed tank and a worn-out anode rod all shorten tank life. Tankless units last longer because there's no tank to rust through, provided they're descaled regularly. More in how long do water heaters last?
What the result means
- Green (under 75% of typical life): maintain and repair.
- Amber (75–100%): budget for a replacement and get quotes before it fails.
- Red (past typical life): replace on your schedule, especially if the heater is in an attic, closet or finished space where a leak would cause damage. See when to replace a water heater.
Frequently asked questions
How can I tell how old my water heater is by the serial number?
Each brand codes the date differently. Bradford White uses two letters (year, then month), Rheem uses the month and year after a letter prefix, and A. O. Smith, State and American use the year and week in the first four digits. Choose your brand above and enter the serial; the tool reads the right code for you.
Does the water heater serial number show the install date?
No. It shows the manufacture date. Most heaters are installed within a few weeks or months of being made, so it is a close guide. For warranty claims, use your installation receipt.
My brand is not listed. What can I do?
Look for a printed MFG DATE on the label first. If there is none, choose "My brand isn't listed" in the tool and send us the brand and serial; we prioritize new decoders by demand.
Is a 10-year-old water heater too old?
It is in the normal replacement window for a tank. It may keep going for years, but start budgeting and watch for leaks, rusty water and rumbling noises.