When to Replace a Water Heater (and When to Repair It)

Most water heaters don’t fail all at once. They give a few months of warning that’s easy to miss until the morning the shower runs cold. Knowing what to look for lets you replace on your schedule instead of on the heater’s.

First, find out how old it is

The manufacture date is coded into the serial number on the label, and each manufacturer codes it differently. Some use the first two digits for the year, some for the month and year, some use a letter. If you can’t decode it, send us a photo of the label and we’ll tell you. On Treasure Valley water, a tank heater that hasn’t been flushed and isn’t on a softener typically lasts eight to twelve years. One that’s been maintained on soft water can go fifteen or more.

Signs it’s a repair

No hot water, tank not leaking. On a gas heater this is usually a thermocouple, igniter or gas control valve. On an electric heater it’s an element or thermostat, or a tripped high-limit switch. All are repairable, and on a heater under about ten years old, repair is usually the right call.

Water too hot or too cold. Almost always a thermostat or control issue, and a quick fix.

A drip at a fitting on top. Supply connections and the relief valve can be replaced without touching the tank.

Pilot won’t stay lit. Thermocouple, nearly every time.

Signs it’s a replacement

Water pooling under the tank. If the leak is coming from the tank body rather than a fitting, the steel has rusted through. There’s no repair. Shut off the water supply to the heater and the gas or power, and call.

Rust-colored hot water only. Cold water runs clear but hot runs brown: the inside of the tank is corroding. The sacrificial anode rod was used up long ago.

Rumbling and popping. A thick layer of hardened sediment is trapping water against the bottom of the tank. A flush may help if it’s early; if the heater is already past ten years, this noise usually means the tank’s days are numbered.

Hot water runs out much sooner than it used to. Sediment is taking up space in the tank and insulating the burner. Combined with age, this points to replacement.

Repeated repairs. If you’ve replaced a part twice in two years on a heater past its tenth birthday, the next repair bill is better spent on a new unit.

What to decide before you replace

Tank or tankless. A tank is cheaper to install and simpler. A tankless unit never runs out, uses less gas and lasts longer, but costs more up front and needs correct gas sizing, venting and scale protection to thrive on our water.

Size. We size by bathrooms, household and peak demand, not by what was there before. The previous owner’s choice may not fit your family.

Code updates. A replacement in the Treasure Valley needs a permit, and the inspection will expect an expansion tank where the system requires one, seismic strapping, proper venting and a relief-valve drain. A quote that skips those isn’t cheaper; it’s incomplete.

Protection. If the house doesn’t have a softener, this is the moment to think about one. A new heater on untreated hard water starts the sediment clock over on day one.

Don’t wait for the puddle

A water heater that fails on a weekday afternoon is an inconvenience. One that fails on the floor of a finished basement on a Saturday night is a flooring claim. If your heater is past ten years and showing any of the replacement signs above, have it looked at while the choice is still yours.