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How Long Should a Water Heater Last? – A Detailed Answer

Fact checked by Stephen Conklin

how long should a water heater lasts

Are you like many homeowners who are wondering if it is time for a new water heater? Answering this question is a breeze if you know how long should a water heater last. While the answer may not be definitive, it gives you an idea of when to prepare for a water heater replacement.

Like everything else, water heaters do not last a lifetime. Many factors can shorten its service life, requiring a replacement sooner than expected.

Join me in discovering the average life of water heaters and how you can extend their service lifespan.

Table of Contents

What Is the Average Lifespan of a Conventional Water Heater With Tank?


Manufacturers have different water heater life spans. One brand might rate its product to last eight years, while another company might say its water heaters can last up to twelve years.

Unfortunately, real-world usage often dictates a shorter service life for tank water heaters. Some families might have their units giving up on them after five years, while others are fortunate to extend their water heater’s service life span to 15 years.

The issue is the anode rod’s construction. This element is crucial in tank water heater systems because it attracts corrosive particles and sediments in the water. It protects the water heater tank from corrosion, extending its lifespan.

Sadly, the anode rod can corrode with continuous use. It cannot perform its function if this happens. In that case, sediments and corrosive compounds deposit in the water heater tank’s bottom. They lead to accelerated degradation, shortening the hot water heater lifespan.

What Is the Average Lifespan of a Tankless Water Heater?

A tankless water heater life expectancy is longer than traditional tank systems because this type does not work continuously. Known as on-demand water heaters, tankless systems only heat the water when someone opens a hot water faucet or showerhead.

However, tankless water heaters are not immune to corrosion, although they do not have an anode rod.

On average, a tankless water heater can last up to 20 years with ideal water conditions and proper maintenance.

What Factors Affect a Water Heater’s Lifespan?


Two identical water heaters can have different lifespans because of the impact of several factors. Knowing how these considerations affect the water heater will help you find a more conclusive answer to how long do hot water heaters last.

Water Hardness Levels

According to the US Geological Survey, more than 90% of US households have moderately hard (over 60 mg/L or 3.5 to 7.0 grains per gallon) to very hard water (at least 10.5 grains per gallon or 180 mg/L).

The remaining ten percent of households have calcium carbonate levels of up to 60 mg/L or 3.5 grains per gallon of water.

The more calcium, magnesium, and other hardness minerals are present in the water, the greater is the risk of limescale formation. Limescale buildup reduces water heater efficiency, undermining the device’s water heating capabilities and shortening the service life of hot water heater units.


Calcium and magnesium are not the only substances that can shorten a water heater’s lifespan. Sediments, dirt, silt, debris, and other particles can also accumulate in the tank’s bottom. These compounds can also clog the water heater’s inlet filters, reducing the water flow to the tank.

Water Consumption

A water heater’s lifespan depends on how hard it must work to deliver sufficient hot water to the household. Using more hot water than the water heater’s production capability can stress the system, leading to premature breakdown of sensitive components.

That is why getting the correct water heater size corresponding to the family’s needs is crucial to ensure water heater longevity.

Build Quality

I cannot help overemphasize this point. Some people might think getting an inexpensive product makes sense because of the savings they get. However, many affordable water heaters have shoddy construction, such as inadequate corrosion protection and insulation.

Of crucial importance is the anode rod. Most water heaters have magnesium anode rods because of their ability to give up electrons more efficiently than aluminum. However, households with high water pH levels or hard water should consider getting a water heater with an aluminum anode rod. Learn more about the top-rated water heater for hard water here, hope this article will help you.


All equipment and machinery require periodic and regular maintenance to ensure optimum working conditions. A meticulous maintenance regimen also lets users identify potential problems before they materialize.

Failure to observe timely repairs and maintenance checks can shorten a water heater’s lifespan. Instead of having an electric or gas water heater last 12 years, it may only last eight years.

Installation Quality

A heavy-duty, well-built water heater means nothing if it’s installed improperly. Gas water heaters must also comply with relevant building codes and guidelines. If not, the family runs the risk of a faulty water heater and gas-related issues.

How Do You Improve a Water Heater’s Service Lifespan?

Extending your water heater’s service life span requires proper maintenance and adhering to the following tips.

Regular Maintenance Checks

Your owner’s manual has a maintenance checklist for every water heater component. It would be best to adhere to these recommendations if you want to extend your water heater’s lifespan.

Buy the Correct Water Heater Size for the Family

One way to avoid overstressing your water heater is by buying the correct size. Always consider your household’s maximum hot water consumption and choose a water heater with a higher capacity.

For example, if your peak use is 50 gallons per hour, you will want a water heater with a first-hour rating of at least 50 gallons.

Flush and Clean the Tank at least Once Yearly

Sediments and other particles can build up at the tank’s bottom over time. That is why it makes perfect sense to flush and clean your water heater every six to twelve months.

Invest in a High-quality Water Softener and Sediment Pre-filter

Installing a pre-filter will prevent sediment accumulation in the water filter. Having a water softener before the water heater can also reduce limescale formation, increasing the water heater’s lifespan.

Consider Adding an Expansion Tank

Heated water expands, undermining the tank’s structural integrity over time. Adding an expansion tank allows the water heater to divert the heated water into the other tank to lessen structural stress on the main tank.

Check the Anode Rod Annually

Assess the anode rod at least once a year to check for its corrosion status. If the anode rod is about 75% corroded, consider replacing it to maximize the water heater’s function.

How Do You Know Your Water Heater Requires a Replacement?

Ideally, you will want to replace the unit at least two years from its terminal service life. Here are several signs that tell you when to replace water heater.

  • Insufficient hot water supply
  • Water not heating up as efficiently as before
  • Increasing water heating bills
  • Signs of corrosion in the water heater and in the water
  • Increasing frequency and number of water heater repairs


How long should a water heater last? With a religious maintenance regimen, you can expect a tank water heater to last up to 12 years, while tankless water heaters can last up to two decades.

Water hardness levels, maintenance issues, water consumption, sediment buildup, water heater quality, and installation quality can impact a water heater’s service lifespan.

Diligent maintenance checks, adding water softeners and filters, installing an expansion tank, and regular cleaning can help extend the water heater’s life expectancy.

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