Tank ages
Most standard residential tanks, gas or electric, last roughly eight to twelve years. Some run longer, some fail early. Hard water, high usage, missed maintenance and high water pressure shorten the span. A tank in a damp basement with no expansion tank and moderately hard municipal water is unlikely to beat the average.
Tankless heaters generally last longer, often around twenty years with regular descaling. Their components can be serviced and replaced, which extends their life further.
A tank's age is printed on the data label stuck to its jacket. The manufacture date is often printed directly; otherwise it is encoded in the serial number, with a code that maker by maker stands for the month and year of build. The maker's website explains its code.
Warning signs
- Rust-coloured hot water while cold runs clear, a sign of internal corrosion.
- Rumbling, popping or knocking as sediment layers boil at the bottom of a gas tank.
- Weeping or dampness around the heater's bottom edge.
- Less hot water than before, as sediment fills space and insulates the burner.
- A relief valve that drips, which may indicate high pressure or temperature.
Repair or replace
A young tank with a single failed part is worth repairing. Thermocouples, gas valves, elements, thermostats and anode rods are all replaceable. An older tank with several symptoms is different. Pouring repair money into a tired tank usually means buying a new one soon after anyway.
| Situation | Usual direction |
|---|---|
| Under about six years, one part failed | Repair |
| Middle age, minor issue | Repair and plan ahead |
| Over about ten years, rust or rumble | Replace |
| Leaking from the tank body | Replace |
Our water heater repair page covers common fixes. If you rent your heater, contact your rental provider first; many rental agreements cover service and replacement.
Extending the life you have
Flushing sediment once a year, checking the anode rod every few years, and keeping household pressure in a normal range all add years. A water softener reduces scale. For a deeper look at the choice between tank and on-demand units, read our note on tank versus tankless, and see water heater maintenance for step-by-step care.
Rented versus owned tanks
Plenty of Durham homes have a rental tank rather than one they own outright. A rental agreement usually covers repairs and replacement, but it also carries a monthly fee and contract terms that can make switching complicated. Look at your bill and agreement before any work, including the buy-out terms, and contact the rental company first if the tank is theirs. If you own the tank, the decisions and the timing are entirely yours, which is a good reason to know its age before it starts to fail.
Asked on the phone
How do I tell how old my water heater is?
Check the rating plate. The date may be printed, or encoded in the serial number. The manufacturer's site explains the code.
Is a rumbling water heater dangerous?
Rumbling usually means sediment. It reduces efficiency and stresses the tank but is not an immediate hazard on its own. Have it checked.
Can I extend my tank's life?
Annual flushing, anode checks and controlled water pressure help. A softener reduces scale.