ember&tankWater heater replacement service

Home / Guides

PROBLEMS & WARNING SIGNS

How long do water heaters last?

Roughly 8–15 years for a tank, 13–15 for a heat pump model and 15–20 or more for tankless, depending on whose figure you use. Your water and your maintenance decide where in that range yours lands.

Written by Victoria StewartTechnical review by Phil Montoya, licensed plumber, October 6, 2026Updated October 4, 2026How we research
Published water heater lifespans by type and source Range chart on a 5 to 30 year scale. Gas or electric tanks: Rheem 8 to 12 years, ENERGY STAR 10 to 12, DOE Energy Saver 10 to 15, DOE rulemaking model averages 14.5 years for gas and 15.1 for electric. Heat pump tanks: ENERGY STAR 13 to 15, DOE model 15.1. Tankless: Rheem 15 to 20 or more, Noritz 10 to 25, Rinnai up to 20, DOE Energy Saver more than 20, DOE model about 20. A dashed line marks year 10, where Rheem and ENERGY STAR suggest planning a tank replacement. Expected life in years, by source published range DOE model average plan at year 10 5 10 15 20 25 30 years Gas or electric tank Rheem 8–12 ENERGY STAR 10–12 DOE Energy Saver 10–15 DOE model, gas 14.5 DOE model, electric 15.1 Heat pump tank ENERGY STAR 13–15 DOE model 15.1 Tankless Rheem 15–20+ Noritz 10–25 Rinnai up to 20 DOE Energy Saver 20+ DOE model ~20 Arrows: open-ended (“15–20+”, “more than 20”). DOE model averages include heaters that last unusually long.
Every source’s range, side by side. Published lifespan ranges by heater type, with DOE’s modeled averages from its efficiency rulemakings shown as dots. The dashed line is year 10, where Rheem and ENERGY STAR say to start planning a tank replacement.

THE SHORT VERSION

  • Gas or electric tank: Rheem says 8–12 years, ENERGY STAR 10–12, DOE’s Energy Saver guide 10–15. Rheem and ENERGY STAR both say to start planning a replacement around year 10.
  • Tankless: Rheem says 15–20+ years, DOE more than 20, Noritz 10–25. Heat pump tanks: ENERGY STAR says they are typically cited at 13–15 years.
  • The ranges differ because they measure different things. DOE’s 15-year storage figure is a modeled average that includes heaters lasting far longer than most; manufacturer figures describe a typical unit.
  • What wears a tank out is corrosion. Hard water, softened water that eats the anode rod faster, high pressure and skipped maintenance all bring that day forward.
  • A warranty is not a life forecast. Rheem sells a kit that adds 4 years to a tank warranty; it is mainly an extra anode rod.

Expected life by type, source by source

There is no single official lifespan. Manufacturers, ENERGY STAR and the Department of Energy each publish their own figure, and they don’t match. Here is every figure we could trace to the publisher’s own page:

Published water heater lifespans
TypeManufacturersENERGY STARDOE Energy SaverDOE rulemaking model (average)
Gas or electric tankRheem: 8–12 years10–12 years10–15 yearsGas 14.5 years; electric 15.1 years
Heat pump tanknot stated13–15 years (“typically cited”)not stated15.1 years (DOE’s electric storage class average, a class that includes heat pump designs)
Tankless (gas)Rheem: 15–20+; Noritz: 10–25; Rinnai: up to 20not statedmore than 20 yearsabout 20 years

Sources: Rheem lifespan articles (March 2026); Noritz (2019); Rinnai FAQ; ENERGY STAR (2024); DOE Energy Saver, tankless water heaters (archived June 2026); DOE final rules for consumer water heaters, 89 FR 37778 (May 2024) and gas-fired instantaneous water heaters, 89 FR 105188 (December 2024).

For a tank, the practical answer is that most last somewhere between 8 and 15 years, and Rheem and ENERGY STAR both say to start planning a replacement once yours passes 10. Rheem attributes the gap between tanks and tankless units to how they work: a tank keeps a full load of water hot all day, while a tankless unit fires only when water flows.

Why the published numbers don’t agree

Manufacturer, ENERGY STAR and Energy Saver ranges are rules of thumb for a typical heater. The DOE rulemaking numbers come from a statistical model built for setting efficiency standards, and they mean something different.

14.5 yrsDOE’s modeled average for gas storage tanks
15.1 yrsDOE’s modeled average for electric storage tanks
~20 yrsDOE’s modeled average for gas tankless heaters
Year 2when DOE’s model starts retiring heaters

Sources: DOE final rules 89 FR 37778 (May 6, 2024), Tables V.2 and V.8 and section IV.F.6; 89 FR 105188 (December 26, 2024), section IV.F.6.

How DOE builds its estimate

For its 2024 water heater rule, DOE combined the age of water heaters reported in national surveys (the Residential Energy Consumption Survey from 1990 to 2020 and the Census Bureau’s American Housing Survey from 1974 to 2021) with historical shipments. From those it estimated a survival curve: the share of heaters still working at each age. It fits that curve with a Weibull distribution, a standard way to model wear-out failures.

In plain words: some heaters fail early, most fail within a band of years, and a few run much longer. DOE’s model starts retiring heaters in year two and has what it calls “a longer tail” of survivors. DOE itself explains that the age most heaters reach is earlier than the average, because “the average takes into account those who live an unusually short or long lifetime.” So a 15-year average does not mean a typical tank reaches 15.

The figure is also disputed. In comments on the rule, Bradford White pointed out that DOE’s previous water heater rule, in 2010, used 13 years, and a group of apartment owners cited an AHRI assumption of 10–13 years. DOE kept its method, saying it now had more evidence and a better survival model. Bradford White also argued that more complex heaters wear out sooner; DOE said it found no evidence that condensing models die younger.

What wears a water heater out

A tank is a steel pressure vessel with a glass lining, and some steel stays exposed at welds and pipe connections. So every tank has at least one anode rod: a bar of a more reactive metal, usually magnesium, that corrodes first and protects the steel. A.O. Smith calls this cathodic protection. When the anode is used up, Rheem says, “the tank itself starts to rust.” Once the steel rusts through, the tank leaks and can’t be repaired. Almost everything that shortens a tank’s life speeds up one of those steps.

How a tank water heater wears out Two gas tank cutaways. The new tank has a full anode rod and a clean bottom. The older tank, after years of hard water, has an anode worn down to its steel core wire, a layer of sediment and scale on the bottom, rust starting where steel is exposed at fittings and welds, and water leaking onto the floor. Below, a list of what speeds this up: hard water, softened water, high pressure without an expansion tank, a hot setting and heavy use. And what slows it down: anode checks, flushing, 40 to 60 psi with an expansion tank, and a moderate temperature. New Years later, hard water full anode, clean bottom Rust starts Anode used up Sediment and scale Leak at fittings and welds, where steel is bare only the steel core wire is left, so the steel is unprotected minerals drop out of heated water the tank can’t be repaired Speeds it up Slows it down • Hard water • Softened water (faster anode use) • High pressure, no expansion tank on a closed system • Hot setting, heavy use • Anode checks and swaps • Regular flushing • 40–60 psi and an expansion tank where needed • No hotter than you need
The same tank, new and after years of hard water. The anode wears down to its steel core wire, and minerals that drop out of heated water settle on the bottom. A.O. Smith lists a spent anode and heavy mineral deposits among the causes of premature tank failure.
What shortens a tank’s life, and the fix
FactorWhat it doesWhat helps
Hard waterHeated hard water drops calcium carbonate scale. USGS says this scale “can reduce the life of equipment.” It settles on the tank bottom and builds up around electric elements (A.O. Smith).Flushing; a softener in very hard water
Softened waterA softener swaps calcium for sodium but leaves the water conductive, so the anode corrodes faster. A.O. Smith also found that a thin scale film protects bare steel; softened water doesn’t form it.Inspect the anode more often
A spent anodeWith only the core wire left, nothing protects the steel. A.O. Smith lists this as a cause of premature failure.Inspect and replace the anode
High pressure and thermal expansionHeated water expands. In a closed system, A.O. Smith says a tank at 50 psi heated just 10° can reach 250 psi. Repeated stretching makes tanks fail early.Pressure at 40–60 psi; an expansion tank on closed systems
High temperature and heavy useLime comes out of solution faster the hotter the water and the more of it you heat (A.O. Smith). Rheem lists heavy household demand among things that speed wear.Don’t set hotter than you need; size the heater properly
Location and airA.O. Smith’s manual says to protect the heater from freezing. On gas models, A.O. Smith warns that chlorine, refrigerant and solvent vapors turn into corrosive acid in the flame and can cause product failure.Keep the heater warm and away from chemical storage

Sources: USGS, Hardness of Water; A.O. Smith Technical Bulletins 13, 43, 44, 45 and 46 and the Signature 100 gas water heater manual (2021); Rheem lifespan article (March 2026).

How much scale are we talking about?

A 2010 lab study by Battelle for the Water Quality Association, the water-treatment industry’s trade group, ran 40-gallon tanks on unsoftened hard water under accelerated conditions. Scale built up at about 1.16 pounds a year in the gas tanks and 2 pounds a year in the electric tanks, against almost none on softened water. The gas tanks also lost efficiency, and the researchers expected scale to shorten electric element life. The sponsor’s members sell softeners, but the direction of the finding matches USGS and the manufacturers.

Where you live matters, mostly through your water

No source we found publishes water heater lifespans by region. What varies by region is the water. A USGS study of about 2,100 domestic wells found hard water “prevalent in the east-central and western United States,” reflecting where carbonate aquifers are. USGS classes water above 180 mg/L of hardness as very hard.

Water hardness classes and where water heater limits fall A horizontal scale of water hardness in milligrams per liter as calcium carbonate, with USGS classes: soft 0 to 60, moderately hard 61 to 120, hard 121 to 180, very hard above 180. A second scale shows grains per gallon: 5, 10, 15 and 20 grains equal about 86, 171, 257 and 342 milligrams per liter. A marker at 200 milligrams per liter shows the hardness limit in Rheem's gas tankless warranty. Below, three ways to find your own number. Water hardness, USGS classes Soft Moderately hard Hard Very hard 0 60 120 180 240 300 360+ mg/L as calcium carbonate 5 10 15 20 grains/gal 200 mg/L Rheem gas tankless warranty limit (scale damage excluded) Find your own number • City water: ask your water utility • Private well: a lab test. mg/L ÷ 17.1 = grains per gallon
Where your water falls on the hardness scale. USGS hardness classes in milligrams per liter, with grains per gallon underneath (1 grain per gallon is about 17.1 mg/L). Rheem’s gas tankless warranty requires hardness of 200 mg/L or less: just past the start of USGS’s very hard class.

Don’t judge your own water from a national map. USGS says its regional data are “not designed to be used to make local decisions” and that hardness for a specific home should come from the local water utility or health agency. Ask your utility; on a private well, a lab test tells you. More in hard water and your water heater.

What actually stretches a heater’s life

Maintenance targets the failure causes above. Manufacturers disagree on intervals, so follow your model’s manual where you have it.

  1. Check the anode rod

    A.O. Smith’s manual says to inspect it after the first six months, then every year, and more often with a water softener. Rheem suggests replacing it every 3–4 years. Anode work usually means shutting off the water and draining some of the tank, so many owners hire it out. See anode rods.

  2. Flush out sediment

    Rheem says flush once a year; A.O. Smith’s manual says every six months. In hard water, more often makes sense. See how to flush a water heater.

  3. Control pressure

    Rheem suggests 40–60 psi at the house. A.O. Smith recommends a pressure-reducing valve when supply pressure is above 60–70 psi and a sized expansion tank on any closed system. This is plumber work.

  4. Keep the temperature reasonable

    Hotter water drops more lime. Set it no higher than you need; see what temperature to set.

  5. Descale tankless units

    Rinnai and Rheem both call for periodic flushing to remove scale from the heat exchanger, yearly in hard water. See descaling a tankless water heater.

Two warranty details show how seriously makers take this. A.O. Smith’s manual says that running a heater without its anode voids the tank warranty, and that tank failures caused by thermal expansion are not covered. Maintenance protects the warranty as well as the tank.

Warranty length is not a lifespan forecast

A warranty is the period a manufacturer agrees to pay for defects. It is a business decision, not a prediction for your house. Rheem’s Professional Classic electric tank, for example, carries a 6-year tank and parts warranty, while Rheem itself says tanks typically last 8–12 years.

  • Longer tank warranties often mean more anode. Rheem’s ProtectionPlus kit turns a 6-year tank warranty into 10 years, or 8 into 12. The kit is a magnesium anode rod and plastic-lined nipples. That is a useful hint: corrosion protection is what the extra years pay for.
  • A different tank material changes the terms. Rheem’s Marathon electric heater has a plastic (polybutene) inner tank that, Rheem says, will not rust; in 2020 Rheem said its 10-year warranty becomes lifetime when registered. Check current terms before you buy.
  • Exclusions follow the failure causes. Anodes are consumables, thermal-expansion failures are excluded (A.O. Smith), and Rheem’s tankless warranty excludes damage from lime and scale.
  • Federal efficiency programs set floors. ENERGY STAR requires at least 6 years on a heat pump model’s sealed refrigerant system and 6 years on a gas tankless heat exchanger.

Use the warranty for what it is: free parts, or a free heater, if something fails early. Labor coverage is often a single year in the certificates above, and start dates and claim rules vary by brand. Details are in our warranty guide.

Tankless and heat pump models age differently

Tankless: no tank to rust, but scale is the enemy

A tankless heater has no tank of stored water, so the classic rusted-through tank failure doesn’t apply. Its weak point is the heat exchanger, where minerals collect. DOE adds that tankless units have “easily replaceable parts that may extend their life by many more years.”

  • Rheem’s gas tankless warranty covers the heat exchanger for 15 years, but requires hardness of no more than 200 mg/L, excludes scale damage and ends after 12,000 hours of operation (about 16 years at an assumed 2 hours a day).
  • In the Battelle study, the tankless units on unsoftened hard water had to be delimed after the equivalent of 1.6 years of use, and their efficiency had fallen from 80% to 72%.
  • Noritz recommends annual maintenance and water treatment where hardness is high.

Heat pump: a tank plus a refrigerant system

A heat pump water heater is an electric tank with a compressor on top. The tank ages like any other, anode and all, and the sealed refrigerant system adds a second set of parts. ENERGY STAR’s 13–15 years is the only published range we found, and its wording, “typically cited,” is cautious. DOE’s rulemaking sets one lifetime per product class, and heat pump tanks sit in the electric storage class, so its model effectively uses the same 15.1-year average for them; Bradford White argued that more complex products wear out sooner and pointed to ENERGY STAR’s 13-year assumption. Warranties offer some protection: Rheem’s hybrid certificate and A.O. Smith’s split-system warranty each cover the tank and parts for 10 years, labor for 1.

Plan the replacement by age, not by accident

ENERGY STAR’s advice is blunt: once a heater is past 10 years, consider replacing it “before you’re left with an emergency decision.” An emergency replacement, it says, can cost more and “typically limit your replacement options to inefficient models.” Planning also gives you time to consider a heat pump model, which ENERGY STAR notes may need ordering time and a longer installation.

  1. Find the age

    Decode the serial number with our age guide and compare it with the table above.

  2. Look at the condition

    Rust at the base, water on the floor, rumbling or rusty hot water on an older tank are reasons to get quotes now. Our repair or replace guide covers which problems are fixable.

  3. Start a fund

    Hypothetical: a tank is 8 years old and you plan to replace it around year 10. Home Depot’s installed range for a tank is $1,600–$2,400, so setting aside $2,000 over 24 months is about $83 a month.

  4. Get quotes before it fails

    Two or three, for the same job. See what a replacement costs.

  5. Know your shutoffs

    Find the cold water valve and the gas valve or breaker today. If the tank does let go, our emergency checklist covers the first 10 minutes.

Common questions

Can a water heater last 20 years?

A tankless unit can: DOE puts tankless life at more than 20 years and Rheem at 15–20+. A tank occasionally does, especially in soft water with regular anode changes, but published tank ranges top out at 10–15 years. Treat a working 20-year-old tank as living on borrowed time and get quotes.

Do electric water heaters last longer than gas?

Slightly, on DOE’s numbers. Its rulemaking model puts the average at 15.1 years for electric tanks and 14.5 for gas, and Rheem has written that electric tanks “may last a bit longer.” Water quality and maintenance matter more than fuel.

Does flushing a water heater make it last longer?

It helps, mainly in hard water. Rheem says removing sediment “extends tank life,” and A.O. Smith lists heavy mineral deposits among causes of premature failure. The anode rod matters at least as much: when it is used up, the steel tank starts to corrode.

Does a water softener shorten water heater life?

It can shorten anode life. A.O. Smith says softened water makes the anode corrode faster, so it should be inspected more often. Softening also stops the scale that hard water deposits, so the usual answer is to keep the softener and check the anode.

Should I replace a 15-year-old water heater that still works?

Plan to. It is past every published tank range. You don’t have to replace it today, but get quotes, choose what you want next and know where the shutoffs are. If it sits where a leak would do serious damage, replacing sooner is reasonable.

How long do tankless water heaters last in hard water?

Less long without treatment. In a 2010 Battelle study for the Water Quality Association, tankless units on unsoftened hard water needed deliming after the equivalent of 1.6 years. Rheem’s warranty requires hardness of 200 mg/L or less and excludes scale damage.

Sources

Sources checked October 4, 2026. Prices, codes and rebates change. Check current details with your installer and local permit office.

  1. Water Heater Lifespan: When to Repair vs. Replace (March 2026) ↗ · Rheem
  2. Tank vs. Tankless Water Heater Lifespan Comparison (March 2026) ↗ · Rheem
  3. A Lifetime of Hot Water with Marathon (2020) ↗ · Rheem
  4. What Goes into the Cost of Installing a Heat Pump Water Heater? (2024) ↗ · ENERGY STAR
  5. When Should You Replace Your Water Heater? (2024) ↗ · ENERGY STAR
  6. Residential water heaters key product criteria (warranty minimums) ↗ · ENERGY STAR
  7. Tankless or Demand-Type Water Heaters (archived copy, June 2026) ↗ · U.S. Department of Energy, Energy Saver
  8. Energy conservation standards for consumer water heaters, final rule, 89 FR 37778 (May 6, 2024) ↗ · U.S. Department of Energy, via Federal Register (govinfo)
  9. Energy conservation standards for gas-fired instantaneous water heaters, final rule, 89 FR 105188 (December 26, 2024) ↗ · U.S. Department of Energy, via Federal Register (govinfo)
  10. Questions about Tankless Water Heaters (2019) ↗ · Noritz
  11. Residential tankless water heater FAQ ↗ · Rinnai
  12. Hardness of Water ↗ · U.S. Geological Survey, Water Science School
  13. Technical Bulletin 13: Mineral build-up ↗ · A.O. Smith
  14. Technical Bulletin 43: Cathodic protection ↗ · A.O. Smith
  15. Technical Bulletin 44: Water softeners ↗ · A.O. Smith
  16. Technical Bulletin 45: Thermal expansion ↗ · A.O. Smith
  17. Technical Bulletin 46: Premature failure ↗ · A.O. Smith
  18. Signature 100 series gas water heater installation and use & care guide (2021) ↗ · A.O. Smith
  19. Battelle finds water softeners aid energy efficiency, appliance life (2010; study funded by the Water Quality Association) ↗ · Contractor magazine
  20. Softened water benefits studies ↗ · Water Quality Association
  21. Professional Classic standard electric water heater (warranty terms) ↗ · Rheem
  22. ProtectionPlus warranty extension kit feature sheet ↗ · Rheem, hosted by Gemaire
  23. Residential tankless gas water heater warranty (AP21265) ↗ · Rheem
  24. Hybrid electric water heater limited warranty AP18539-1 (2017) ↗ · Rheem, hosted by Home Depot
  25. Split-system heat pump water heater limited warranty (2025) ↗ · A.O. Smith
  26. Water heater installation cost guide (installed price ranges) ↗ · Home Depot
Get a water heater quote

How we research

KEEP READING

PROBLEMS & WARNING SIGNS

How old is my water heater? Reading the serial number by brand

The manufacture date is on the label, usually hidden in the serial number. Each brand hides it differently, and two codes that look alike can mean different things.

Read the guide ↗
PROBLEMS & WARNING SIGNS

Repair or replace your water heater?

Where the water is coming from settles most cases. When it doesn’t, the heater’s age, the repair price and the warranty decide, roughly in that order.

Read the guide ↗
OWNERSHIP & MAINTENANCE

Water heater maintenance: a schedule that actually matters

Most water heaters need about an hour of attention a year. Which hour depends on the type: sediment and the anode rod for tanks, scale for tankless units, a filter and a drain line for heat pumps.

Read the guide ↗
OWNERSHIP & MAINTENANCE

Read the warranty before you compare prices.

Tank, parts and labor coverage are different promises from different companies.

Read the guide ↗

READY TO REPLACE IT?

Start with a photo
of your old heater.

Get a water heater quote

No payment. No booking. You decide who gets your details.