A water heater usually gives little warning before it fails, and a tank that lets go can flood a basement. Knowing how long your type typically lasts tells you when to start planning a replacement instead of waiting for the leak.
According to the DOE, a storage tank water heater lasts 10 to 15 years, a tankless one about 20, a heat pump water heater 10 to 15 and a solar system about 20. ENERGY STAR advises replacing a tank water heater proactively once it's over 10 years old, before it fails.
Water Heater Lifespan Calculator
Your unit's age against the DOE expected-life range.
Lifespan by type
| Type | Typical lifespan (DOE) |
|---|---|
| Storage tank, gas or electric | 10 to 15 years |
| Tankless (on-demand) | About 20 years |
| Heat pump water heater | 10 to 15 years |
| Solar | About 20 years |
ENERGY STAR also gives tankless water heaters a life expectancy of 20 years, and notes that without a tank, there's no tank to leak. Enter your unit's type and age in the calculator to see where it falls in its range.
What the warranty tells you about lifespan
A storage tank's warranty length is a rough proxy for how long the maker expects it to resist corrosion. Tanks are sold in tiers, and a longer-warranty model usually carries more corrosion protection inside, most often a larger or second sacrificial anode rod, and sometimes a heavier element.
The anode is the key part here. It is a metal rod that corrodes in place of the steel tank, so a bigger or second anode delays the day the tank itself starts to rust. That is the same mechanism that extends real-world life, which is why warranty tier and expected lifespan tend to move together within the DOE's 10 to 15 year range.
Treat the tier as a planning signal rather than a promise. A longer warranty is worth more where water is hard or where you plan to stay in the home, because the extra anode buys time against the same process that ends a tank's life.
Finding your water heater's age
The manufacture date is usually encoded in the serial number stamped on the rating plate, the sticker or metal label near the top of the unit. Most formats pack the month and year into the first few characters, in one of two common patterns.
One pattern is four digits read as year then month, so a serial beginning 2406 points to the sixth month of 2024. Another is a letter for the month followed by digits for the year, with the letters running in order and skipping the letter I so it is not mistaken for a 1. If a decoded date lands after the day you bought the unit, you most likely read the digits in the wrong order.
Formats vary by maker, and manufacturers do not publish them as official consumer documents. For a brand-by-brand method and worked examples, see our HVAC serial number decoder; for a water heater, the maker's support line or product-registration lookup can confirm the date.
Signs a water heater is failing
- Water leaking from the tank itself, not a fitting or valve. A corroded tank can't be repaired.
- Rusty or discolored hot water, which can mean the tank is corroding inside.
- Rumbling or popping as it heats, from sediment built up on the bottom of the tank.
- Less hot water, or water that won't stay hot, from a failing element, thermostat, burner or sediment.
- Its age: past the top of its range, it's on borrowed time.
Repair or replace?
Work from the unit's age against the DOE range and the part that failed. Within the 10 to 15 year window for a tank, a failed element, thermostat, igniter, gas valve or relief valve is a repairable part, and on a younger unit fixing it is usually the better call.
A tank leaking from the body itself is the exception: corroded steel cannot be repaired, so a leaking tank means replacement whatever its age. Rusty hot water and rumbling point the same way, since both trace back to the tank corroding or filling with sediment.
Past 10 years, ENERGY STAR's advice is to plan the replacement before it fails. Doing it on your schedule lets you choose the right type and size, and line up a rebate if you qualify, instead of taking whatever is in stock during an emergency.
Hard water and lifespan
Hard water carries dissolved minerals that drop out as scale when the water is heated. In a tank that scale settles as sediment on the bottom, where it insulates the burner or buries the lower element and makes the heater run hotter. In a tankless unit the same scale coats the heat exchanger and narrows its passages.
Hard water also uses up the sacrificial anode faster, so the tank loses its corrosion protection sooner. The combined effect pushes a unit toward the lower end of its DOE range rather than the upper end, which is why flushing and anode checks matter most where water is hard.
How to help it last
- Flush sediment on the manufacturer's schedule, more often where water is hard.
- Check the anode rod, which corrodes in place of the tank; replacing it when it's used up protects the tank.
- Test the temperature and pressure relief valve as the manual directs.
- Descale tankless units on schedule, especially with hard water.
Planning the replacement
Replacing before failure lets you compare options. A heat pump water heater uses less than half the energy of a standard electric storage water heater, according to ENERGY STAR, and income-qualified households may get a HEAR rebate of up to $1,750. See our water heater guide, the sizing calculator and tankless costs.
Frequently asked questions
How long does a water heater last?
A storage tank lasts 10 to 15 years, a tankless unit about 20, and a heat pump water heater 10 to 15, according to the DOE.
Should I replace a 10-year-old water heater?
ENERGY STAR advises replacing a water heater proactively once it's over 10 years old, before it fails. A tankless unit typically lasts longer.
Do tankless water heaters last longer than tanks?
Yes. The DOE puts tankless units at about 20 years against 10 to 15 for storage tanks.
What shortens a water heater's life?
Sediment and hard water, a used-up anode rod, high water pressure and skipped maintenance. Following the manufacturer's maintenance schedule helps it reach the upper end of its range.
How long does a water heater last without maintenance?
Skipping flushes and anode checks lets sediment and corrosion build up, which tends to push a tank toward the lower end of the DOE's 10 to 15 year range or below it. Keeping to the manufacturer's maintenance schedule is what helps a heater reach the upper end of its range.
Does a bigger water heater last longer?
No. The DOE lifespan ranges are set by type, not capacity, and what ends a tank's life is corrosion of the steel and the state of its anode rod, not its size. A larger tank holds more water but ages by the same process as a smaller one.
How often should I replace the anode rod?
Inspect the anode on the schedule in your manual and replace it once it is substantially consumed, since a used-up rod no longer protects the tank. Hard water and higher temperatures use it up faster, so it needs checking sooner in those conditions.
How long do water heaters last in hard water?
Hard water pushes a tank toward the lower end of the DOE's 10 to 15 year range, because scale and faster anode consumption speed up the corrosion that ends its life. Regular flushing and anode checks claw back some of that lost life.