How Old Is Your Water Heater? Here's How to Find Out: Brand by Brand

Most homeowners don't think about their water heater until something goes wrong. But knowing your unit's age is one of the most useful pieces of information you can have; it tells you whether a repair makes sense, whether a replacement is overdue, and whether you're living with a ticking time bomb in your utility closet.

Tank water heaters typically last 8-12 years. If yours is approaching or past that window, understanding its age is the first step toward making a smart decision about what comes next.

The good news: every water heater has its manufacturer's date encoded in its serial number. Here's how to read it for the most common brands installed in Atlanta-area homes.

Where to Find Your Water Heater's Serial Number

Before decoding anything, you need to locate the serial number. On most tank water heaters, the model number is printed on a sticker on the upper portion of the tank, usually near the top, on the side facing outward. The label also includes the model number, gas/electric specs, and BTU rating.

On tankless units, the serial number is typically on the front panel or inside the access cover. If the sticker has faded or been painted over, contact the manufacturer with your model number; they can often help trace the unit.

Bradford White Water Heaters

Bradford White uses an alpha code system where the first letter of the serial number represents the year and the second letter represents the month. The letters I, O, Q, R, U, and V are skipped.

Year codes:

A = 1984 or 2004 B = 1985 or 2005 C = 1986 or 2006 D = 1987 or 2007 E = 1988 or 2008	F = 1989 or 2009 G = 1990 or 2010 H = 1991 or 2011 J = 1992 or 2012 K = 1993 or 2013	L = 1994 or 2014 M = 1995 or 2015 N = 1996 or 2016 P = 1997 or 2017 S = 1998 or 2018	T = 1999 or 2019 W = 2000 or 2020 X = 2001 or 2021 Y = 2002 or 2022 Z = 2003 or 2023

Month codes:

• A = January, B = February, C = March, D = April
• E = May, F = June, G = July, H = August
• J = September, K = October, L = November, M = December

Example: A serial number beginning with "NF" was manufactured in June 2016 (or June 1996). Given that most 1996 units have long since been replaced, if you see a two-letter code at the start, assume the more recent decade applies.

Bradford White is one of the most common brands our technicians encounter in homes, and many units in the 2010-2015 range are now well past their useful life. If your Bradford White starts with G, H, J, K, L, or M, it's worth considering whether repair or replacement makes more sense. Our team at Dalmatian can help you evaluate. Visit our water heater repair and replacement page to learn more.

A.O. Smith Water Heaters

A.O. Smith uses several serial number formats depending on the era of manufacture. Here are the most common:

• Style 1 (most common): The third and fourth digits represent the year. Example: serial number 1210A002243 manufactured in 2010.
• Style 2: The first two digits represent the year. Example: AF04A093001 manufactured in 2004.
• Style 3: The first two digits represent the year. Example: CG03-1495366-S29 manufactured in 2003.
• Style 4: The first and second digits represent the year. Example: E07A13549 manufactured in 2007.

If you're unsure which style applies, A.O. Smith's website lets you enter your model and serial number to pull up your unit's details.

Rheem Water Heaters

Rheem embeds the manufacture date in the serial number, but uses multiple formats across different product lines:

• Style 1: Characters 2-3 = month, characters 4-5 = year. Example: R0884B10488 August 1984.
• Style 2: Characters 2-3 = month, characters 4-5 = year. Example: RHLN0106534307 January 2006.
• Style 3: Characters 2-3 = week of year, characters 4-5 = year. Example: A141511869 14th week of 2015.
• Style 4: Character 2 = month, characters 3-4 = year. Example: D1114A441408265A November 2014.

Rheem is one of the more complex brands to decode because the prefix varies (R, RH, RHLN, RHNG, RU, etc.). When in doubt, bring your serial number to a licensed plumber — or call Dalmatian and we'll identify it for you.

Ruud Water Heaters

Ruud is a sister brand to Rheem and uses very similar serial number structures:

• Characters 2-3 typically represent the month, characters 4-5 the year, same as Rheem Styles 1 and 2.
• Some formats use the first two digits for the year and characters 3-4 for the week of manufacture.

If you have a Ruud unit and are unsure of its age, the decoding logic is nearly identical to that of a Rheem unit. If you're having trouble, a quick call to a water heater professional in Atlanta can get you a definitive answer.

State Select Water Heaters

State Select uses the first four digits of the serial number to encode the manufacture year and week:

• Style 1: First two digits = year, next two = week. Example: 1210A002243 10th week of 2012.
• Style 2: Same format. Example: H765662231 5th week of 1976 (very old unit).
• Style 3: First two digits = year, next two = week. Example: AF04A093001 4th week of 2009.
• Style 4: First four digits encode year and week. Example: 1735107397129 35th week of 2017.

Navien Tankless Water Heaters

Navien encodes a full manufacture date (year, month, and sometimes day) in the serial number:

• Style 1: Characters 1-2 = year, 3-4 = month, 5-6 = day. Example: 9545J1152752044 May 27, 2011.
• Style 2: Characters 1-2 = year. Example: 7414C14X1771143 2014.
• Style 3: Characters 5-6 = year, 7-8 = month, 9-10 = day. Example: 9262-20081208-1027 December 8, 2008.

What Does Your Water Heater's Age Actually Mean?

Now that you know how old your unit is, here's what to do with that information.

Under 6 years old:

Your water heater is in its prime. As long as it's performing well and there are no signs of corrosion or leaks, routine maintenance (flushing sediment, inspecting the anode rod) is all you need.

6-10 years old:

Pay attention to performance. If you're noticing inconsistent hot water, strange noises (popping or rumbling), or any signs of rust-colored water, it's worth having a plumber assess whether the unit is nearing the end of its life. Repairs may still make sense, but start the replacement conversation now.

10-12+ years old:

This is the danger zone for most tank water heaters. Even if your unit seems to be working, internal corrosion and sediment buildup are often happening invisibly. A failure at this age is a matter of when, not if, and a catastrophic leak can cause thousands of dollars in water damage. We generally recommend proactive replacement over reactive emergency service for units in this range.

Atlanta's hard water accelerates wear on water heater components. The calcium and mineral content in metro Atlanta's water supply speeds up sediment accumulation and anode rod depletion compared to areas with softer water. That means an Atlanta water heater may reach the end of its effective life on the earlier end of the typical range.

Signs It's Time to Repair or Replace (Regardless of Age)

Age is the primary indicator, but these symptoms mean you need a professional evaluation sooner rather than later:

1. Rust-colored or discolored hot water is often a sign of internal tank corrosion
2. Popping, rumbling, or banging sounds, caused by sediment buildup cooking against the heating element
3. Water pooling around the base of the tank could indicate a slow leak or a failing pressure relief valve
4. Inconsistent hot water temperature, thermostat, or heating element issues
5. Running out of hot water faster than usual, sediment displacement is reducing the effective tank capacity
6. Visible rust or corrosion on the unit, inlet/outlet connections, or pressure relief valve

Some of these issues are repairable; a failing thermostat or a stuck pressure relief valve doesn't necessarily mean the whole unit needs to go. Others, like internal tank corrosion, are a signal for replacement. The only way to know for sure is a professional diagnostic.

Dalmatian Plumbing Can Help You Decide

If you've decoded your serial number and found you're sitting on a 10+ year old unit, or if you're seeing any of the warning signs above, Dalmatian Plumbing is here to help Atlanta homeowners make the right call.

Our licensed technicians have 75+ years of combined experience working on every major water heater brand. We carry parts on every truck, offer same-day service, and provide an honest assessment of whether repair or replacement makes more financial sense for your situation. With 4.9 stars and 600+ Google reviews, we've earned the trust of homeowners across Marietta, Smyrna, Kennesaw, Alpharetta, Lawrenceville, and the rest of metro Atlanta.

Whether you need a straightforward repair or a full water heater replacement in Atlanta, our team will walk you through your options clearly, no pressure, no upsells you don't need.

Ready to find out where you stand? Visit our Atlanta water heater services page or give us a call. We'll help you figure out exactly what your water heater needs, and what it doesn't.

Learn more about our water heater repair and replacement services and see why Atlanta homeowners have trusted Dalmatian Plumbing for over 25 years.