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Home » Water Heaters » How Long Do Hot Water Heaters Last?

How Long Do Hot Water Heaters Last?

By: David Trinh
Last Updated:
How Long Does a Water Heater Last

When you’re looking to purchase a new water heater or when you’re considering replacing your current one, the main thing you need to know is how long should a water heater last. The question is more complex than it may seem at the outset, as there are a number of factors at play.

In this article, we will tell you everything you need to know about the average life of water heaters, how to expand their lifespans, and how to determine if you need a new water heater.

Average Lifespan of Hot Water Heaters Compared

Type of Water Heater
Average Life Span of Water Heater
Tank Gas
8 to 12
Tank Electric
10 to 15
Tankless Gas
20 years
Tankless Electric
20 years

How Long Do Gas Water Heaters Last?

tank water heater in garage

First, let’s look at the lifespan of a conventional gas water heater. These types of heaters tend to last between 8 and 12 years.

The most common reason a gas water heater fails is corrosion. The heater has an anode rod to protect its interior lining. The rod attracts corrosive particles through electrolysis. After some time, the rod itself becomes too corroded to continue attracting particles. Instead, the particles drop to the bottom of the tank and start eating away at the lining. This prevents the hot water tank from being able to carry out its job.

How Long Do Electric Water Heaters Last?

electric water heater hanging on the wooden wall

An average electric water heater life expectancy is just a few years longer than a gas water heater lifespan at around 10-15 years.

The two types of water heaters work in much the same way. In fact, the only difference is that the water in an electric system is heated with upper and lower heating elements that extend into the tank. In a gas heater, a gas burner heats the water from below.

As with a gas water heater, an electric water heater lifespan is dependent on maintenance and repairing broken elements. It tends to need replacing once too much sediment starts to build up at the bottom of the tank. Early on, it is possible to drain the tank of this sediment. As the tank ages, however, this process becomes less effective.

How Long Does a Tankless Water Heater Last?


Water heaters that have a tank, no matter if they run on gas or electricity, are considered traditional water heaters. More modern models have no tank at all. So, how long do tankless water heaters last?

As you can see in the chart above, tankless water heaters (like conventional heaters) are available as gas or electricity powered. Unlike traditional heaters, though, there is little difference in lifespan between tankless gas and tankless electric water heaters.

In both cases, they last for around 20 years. With proper care, however, they can keep providing you with hot water for longer — even up to 30 years!

The reason for the longer tankless water heater life expectancy is the difference in design. As the name suggests, rather than storing hot water in a tank, a tankless water heater only receives water at the moment a hot water tap is turned on.

Over time, leaks can develop in the heat exchanger of a tankless water heater. Once this leads to corrosion, you’ll need a replacement. Luckily, these leaks don’t tend to occur until a water heater is at least 15 years old.

Which Type of Heater Is the Most Reliable?

Simply knowing the answer to “how long do water heaters last?” doesn’t give you the full picture of what type of heater is the best. You also need to know which kind of heater is the most reliable — which water heater will provide you with the best service over the long term? The answer to this will depend somewhat on your needs and what you are looking to gain from your water heater.

Amount of Water Heated

Tank water heaters and tankless water heaters can both provide the same amount of water heated.

With a tank model, the exact amount of water your heater will provide you with depends on the size of your tank. It’s important to choose the appropriate size for your household. For particularly large amounts, gas tank water heaters are better than electric heaters, as they heat considerably more water per hour.

On the other hand, tankless heaters heat the water on demand. With tankless water heaters, you will need to look at the GPM capability of the individual water heater to determine how much hot water can be produced at one time.

Overall, tankless water heaters are better for this specification because unlike tank heaters, they produce hot water continuously at the GPM amount they are able to. With a tank model, once you use all of the hot water stored in the tank you run out of hot water. If you purchase a tankless water heater that has a high GPM capability they will be able to produce the same amount of heated water.

Heat Loss

The main issue with having hot water ready at all times is heat loss. This is the case for both types of tank water heaters and not an issue at all for tankless heaters. You can mitigate the problem to an extent by adding insulation to the tank, but there will still be some heat loss.

Overall, tankless water heaters are better in this specification.

Hot Water During a Power Outage

Both tank and tankless gas water heaters can supply you with hot water during a power outage. This can be an advantage if you live in an area that suffers from electricity cuts more than just occasionally. It will ensure that you have reliable access to hot water at all times.

Overall, either type of water heater that is powered by gas is best for this specification.

Low Risk of Accidents

All types of water heaters can suffer from damage and wear if they lack regular maintenance. However, some types of accidents are far worse than others. For instance, gas heaters carry the highest risk — a gas leak in the heater or a pipe can lead to an explosion.

The storage tanks of traditional heaters (gas or electricity) can also suffer from water leaks. Corrosion can mean anything from a small drip or a considerable amount of water escaping. If your water heater is indoors, this could result in a flood.

For these two reasons, tankless electric water heaters are the most reliable in terms of safety.

Fast Heating Capabilities

Tankless water heaters provide you with hot water at the instant you turn on the faucet. Similarly, having hot water ready in a storage tank means that there’s no need to wait for the water to heat up. The problems only start when you deplete the hot water supply in a tank — it can take a long time to replenish. Electric heaters are slower to replenish their tank than gas heaters.

Overall, gas tankless water heaters are the best and most reliable for the fastest heating capability.

Using Multiple Sources of Water

If multiple members of your household want access to hot water at the same time, a lower powered tankless water heater may prove to be unreliable.

For instance, if you have more than one shower in your home, you may still find that only one person is able to shower at a time if your heater isn’t sized correctly. You may also need to refrain from taking a shower while doing a load of laundry using hot water — that is, if you want to avoid a sudden burst of cold water.

That being said, if you choose a tankless water heater with the required GPM for your household this shouldn’t be an issue and a tankless heater can work even better than a conventional unit for multiple sources of water.

Need for Repairs

Tank water heaters have a simpler setup than tankless models. This can often mean less need for repairs and other types of maintenance. Furthermore, when repairs are necessary for a conventional heater, it tends to be obvious where the problem lies, meaning the issue is quicker to fix.

Overall, conventional tank models are easier to repair due to the simplicity but tankless water heaters last longer and may not have as large of repair issues.

How to Expand Your Water Heater Lifespan

We’ve mentioned maintenance a few times when talking about how long do hot water tanks last. Adequate, regular maintenance is critical whatever your water heater — it can mean the difference between needing to replace the heater right after your warranty expires and being able to keep it for several more years.

There are a number of basic things you can do to keep your water heater in top condition. Just bear in mind that all the following require turning off the water heater first and being careful — the water you release may be scolding hot.  If you don’t have experience working with water heaters, we always recommend consulting with a quality water heater technician for any servicing and repair issues.

Below, we will walk you through how to determine the right tankless heater for your home water situation.

1. Check the Pressure-Relief Valve

Conventional water heaters have a pressure-relief valve. This is designed to stop pressure building up inside the tank and causing an explosion. However, it is only able to prevent an explosion if it is working properly. For this reason, you need to check that it is functioning correctly on a regular basis.

To run the test, place a bucket under the discharge pipe. Then, raise the lever of the pressure-relief valve. Water should come out of the pipe. If none does, you need to replace the valve.

2. Take a Look at the Anode Rod

We’ve already mentioned that the anode rod corroding is a major cause of failed tank water heaters. Checking that your anode rod is in good condition is a simple way to expand your hot water heater lifespan. Find the rod screwed to the top of your tank gas or electric heater. If there is any sign of corrosion, replace the rod immediately. This will prevent your tank from developing a leak. Replacing the anode rod often can help extend the water heater useful life to as much as 12 years.

3. Remove Limescale

Even a small amount of limescale can stop your water heater from working efficiently. You can clear away limescale buildup simply by flushing your heater with undiluted white vinegar. The procedure is different according to whether you have a tank or tankless water heater.

For a tank water heater, open a faucet just slightly to stop a vacuum occurring. Then, attach a hose to the drain valve and turn off the supply of cold water. Remove some of the water from the tank to make space for the vinegar. After this, you can turn off the faucet. Remove the anode rod and pour in the vinegar. Put the anode back (this is a good opportunity to replace it with a new one, if necessary) and turn the cold water supply back on. Leave the vinegar for at least six hours before draining it and refilling your tank with water.

For a tankless water heater, you need to remove the lid and close all three water valves. Remove the purge port valve caps to release pressure in the heater. Then, attach hoses to each of the valves. Reopen the valves and flush the water heater with vinegar. Put the valve caps back on and remove the filter. Clean the filter by rinsing it with water and then replace it. Finally, replace the cover and restart your heater. Your manufacturer’s manual will provide you with instruction on how to do this safely.

4. Flush Out Sediments

Tank water heaters need flushing once or twice a year. This removes any sediment sitting at the bottom of the tank. Keep flushing the water until no sediment is left — it should take around 2 to 3 gallons of water.

If you continue to flush your tank but there is still sediment or if the water has a rust color, your heater is likely no longer working safely. In this case, it needs replacing as soon as possible. Another indication that you need a new water heater is rumbling noises. These should go away after you flush the tank. If they persist, there is something seriously wrong with your heater.

5. Inspect the Gas Lines

If you have a gas water heater (of any type), you need to inspect the pipes often. Look for signs of corrosion and for cracks. In the case you suspect that you do have a leak, seek a professional HVAC service. Even a small leak can be extremely dangerous.

6. Look for Water Leaks

If your water heater is outdoors, you may not notice that is leaking. Cracks in the heater or a puddle below the heater on the floor suggest severe damage — and the need for a replacement.

Bear in mind, the first time you use a gas heater, it will create some condensation. You may notice a small amount of water in the drain pan. This is normal — the water will go away as soon as the heater reaches the correct temperature.

This article has answered two questions: how long are water heaters good for and how can you make your heater last longer. With this knowledge, you’ll be able to choose the right type of water heater for your home and increase your water heater lifetime. 

Be sure to check out our review of the top tankless models before purchasing. 

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David Trinh
David is an expert in all things plumbing, heating, cooling, and water treatment. He got his start in the plumbing business working on fixing all types of home improvement issues including water leaks, broken toilets, appliance installation, and more. Over time, he learned a ton about installing and choosing the correct water treatment products for homeowners.

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