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Rheem / Ruud water heaters

How old is my Rheem water heater?

Enter the serial number from the label. The date comes from Rheem's documented serial rules, not a guess.

Look for “Serial No.” or “S/N” on the label. Spaces and dashes are fine.

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How to read a Rheem water heater serial number

Rheem, Ruud and Richmond water heaters share one serial-number system. Since 2012 the serial starts with a plant letter followed by the week and year. Older heaters start with the month and year.

  • Plant letter + week + year (2012 onward)

    Example: M141209135 (Rheem) was made in April 2012. Since 2012, Rheem water-heater serials start with a plant letter ("M" = Mexicali), then two digits for the week and two for the year: week 14 of 2012.

  • Month + year + plant code (before 2012)

    Example: 0912D01234 (Rheem) was made in September 2012. On Rheem water heaters built before 2012, the serial starts with the month and then the year: "09" is September and "12" is 2012.

Not decoded yet: Older Paloma-built tankless serials (e.g. 05.05-000021) and some 16-character serials are not decoded because sources disagree. If the label prints a MFG DATE, that date is authoritative.

Where to find the serial number

The rating label is on the side of the tank: near the gas control valve on gas models, or above the upper heating-element cover on electric models.

Rheem water heater model numbers

If the brand name isn't visible on the label, the model number can help. Model numbers like these follow Rheem's published nomenclature:

How long does a water heater last?

A typical water heater lasts about 8–12 years. That's a general estimate: maintenance, usage, climate and installation all matter, and age alone doesn't tell you a unit's condition.

Range from A. O. Smith: when to repair or replace a water heater and Lennox: when to replace a water heater.

Rheem water heater recalls

From the U.S. Consumer Product Safety Commission, checked 2026-09-29. A decoded result checks your model number against recalls live.

Questions

How can I tell how old my Rheem water heater is?
Find the serial number on the rating plate and enter it above. Rheem water heaters use the Rheem / Ruud water heaters serial format, which includes the manufacture date. For example, M141209135 was made in April 2012: Since 2012, Rheem water-heater serials start with a plant letter ("M" = Mexicali), then two digits for the week and two for the year: week 14 of 2012.
Where is the serial number on a Rheem water heater?
The rating label is on the side of the tank: near the gas control valve on gas models, or above the upper heating-element cover on electric models.
How long does a water heater usually last?
A typical service life is about 8–12 years. That's a general estimate: maintenance, usage, climate and installation all matter, and age alone doesn't tell you a unit's condition.
Do Ruud water heaters use the same serial format?
Yes. Rheem and Ruud use the same serial-number conventions (Rheem / Ruud water heaters), so the same decoding rules apply.
How reliable is the result?
The Rheem / Ruud water heaters rules come from documented sources, but they're in Beta while we check more real-world examples, so results are capped at medium confidence. If a serial doesn't match a documented format, we say so instead of guessing.

Same serial format: Ruud water heater

Other Rheem equipment: furnace, air conditioner, heat pump, tankless water heater

Sources

Rules last reviewed 2026-09-28. These rules are in Beta while we verify more real-world examples, so results are capped at medium confidence.

Manufacture dates are decoded from manufacturer serial-number conventions and available documentation. Serial formats can change. Verify critical equipment information with the manufacturer when necessary.