Water Heaters
How Long Does a Water Heater Last?
The short answer
A conventional tank water heater typically lasts 8–12 years. A tankless unit can last 15–20 years or more. Lifespan depends on water quality, maintenance, and how heavily the unit is used — not just the brand.
Common symptoms
- Water heater is 8+ years old
- Rumbling or popping sounds from the tank
- Water isn't as hot as it used to be
- Rust-colored hot water
- Visible rust on the tank exterior or fittings
Most likely causes
- —Sediment buildup from hard water
- —Corrosion of the tank's glass lining
- —Sacrificial anode rod depleted
- —Hard water scaling on elements or the burner
- —Lack of annual maintenance flushing
Safe things you can check
- ✓Check the serial number label — the first digits often encode the manufacture date.
- ✓Drain a few gallons from the tank's drain valve — if rusty water comes out, the tank may be corroding internally.
- ✓Listen for rumbling or popping — that's sediment heating and popping inside the tank, a sign it needs flushing.
When to call a professional
If your heater is 10+ years old and showing any of these signs, it's wise to plan for replacement before it fails. A tank that leaks from the bottom has already failed — replacement can't wait.
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Reviewed by Paul Hall, Owner & Licensed Plumber
The Classic Plumber · Knoxville, TN · License #4268
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