The short answer

8–12 yearstypical water heater lifespan

That range is for conventional tank water heaters (gas or electric), which most homes have. Gas units tend to fail a year or two sooner than electric, and water quality matters more than brand — in a hard-water area, a never-flushed tank can fail in as little as 6 years. Tankless units are a different clock entirely: 15–20+ years with periodic descaling. If you don’t know your unit’s age, the manufacture date is encoded in the serial number on nearly every brand — search the brand name plus “serial number date”.

What shortens or extends its life

Shortens it

• Hard water — dissolved minerals settle as sediment that insulates and overheats the tank bottom• A consumed anode rod — once it’s gone, corrosion starts on the tank walls themselves• High water pressure (or a missing expansion tank) stressing the tank with every heating cycle• Temperature set above 130°F, which accelerates both scale buildup and corrosion• A location that floods or freezes — garage and crawl-space units live harder lives

Extends it

• An annual flush that clears sediment before it hardens into a layer• Replacing the anode rod every 3–5 years — a ~$30 part that can double tank life• A water softener, if your water is hard• Keeping house pressure near 60 psi with a working pressure regulator

Warning signs it’s failing

• Rusty or brown hot water while the cold runs clear — that points at the tank, not the pipes• Rumbling or popping during heating: water boiling up through a sediment layer• Moisture, drips, or rust streaks at the base or around fittings• Hot water running out noticeably faster than it used to• Any leak from the tank body itself — that’s terminal; tanks aren’t repairable

What replacement costs

$1,200–$3,500 installedfor a like-for-like tank replacement, varying with capacity, fuel type, and the code upgrades your area requires (expansion tank, drain pan, venting). Switching to tankless typically runs $2,500–$5,500 once venting and gas-line changes are in. Get at least two quotes — the price spread on identical units is real.

Maintenance that extends its life

Flush the tank once a year

Drain a few gallons — or the full tank if it’s been years — to clear sediment. Twenty minutes with a garden hose.

Test the T&P relief valve yearly

Lift the lever, confirm water flows and then stops. A stuck valve is a safety problem, not just a longevity one.

Check the anode rod every 3 years

Replace it once it’s mostly eaten away. This is the single highest-leverage water heater task there is.

Keep the thermostat at 120–125°F

Hot enough for comfort and safety, cool enough to slow scale and corrosion.