The Average Life Expectancy of a Tankless Water Heater (All Brands)

Tankless water heaters are great because you never run out of hot water. But how long does it take for one to break down? And what factors can affect its lifespan?

Tankless water heaters are expected to last about double the number of years as traditional storage tank water heaters. Without a huge steel tank that is so susceptible to potential leaks, corrosion, and buildup, a tankless water heater can last up to 20 years if properly maintained.

There are a few things that can prolong or shorten that lifespan that you will want to keep in mind if you have or are thinking of buying a tankless water heater. In this article, I’ll talk about all the different factors that can affect the lifespan and give a few tips for you to get the most life out of it! 

How Long Will My Tankless Water Heater Last?

Tankless water heaters are great because they offer an unlimited supply of hot water. They also are extremely energy efficient and can save you quite a bit of money on your utility bills.

But perhaps one of the best things about tankless water heaters is that they last so much longer than traditional storage tank water heaters. In fact, according to Energy Star, a typical tankless water heater will last up to 20 years or more!

Here are how some of the top manufacturers compare when it comes to expected lifespan:

BrandAverage Lifespan
Rheem15-20 years
A.O. Smith25+ years
EcoSmart20 years
Bosch20 years
Stiebel Eltron20-30 years

It’s also worth noting that water quality and where you have installed your tankless water heater can affect the lifespan, so let’s talk a bit more about that. 

Water Quality

The quality of the water running through your pipes and to and from your tankless water heater can play a major role in how long it lasts. 

Hard water is rough on any plumbing system because it causes buildup over time which will make the system work harder. So hard water, or water that contains high levels of chlorine or other chemicals, could shorten the lifespan of your tankless water heater. If this happens, you may need to replace your water heater sooner than expected.

To avoid this problem, you can look for a tankless water heater that is designed specifically for low mineral-content water. These units typically come with a built-in filter that removes most of the impurities before they reach the heating elements.

Alternatively, you could install a water softener to make sure the water flowing through your system is high-quality water.

Location of your water heater

One of the best things about tankless water heaters is that they are so small and compact and can fit almost anywhere. But you want to make sure you choose the right location to install your tankless water heater so that you can get the most life out of it. 

Installing it inside your home would be ideal because it would protect it from direct sunlight and rain, which could cause corrosion and decrease the lifespan of your unit. 

Since they are so compact, many people choose to instal them in a closet, cupboard, or even under the sink.

If you want to place your tankless water heater outside, make sure you choose a brand that is built to withstand the weather and comes equipped with a freeze protection safeguard.

Why Is the Tankless Water Heater’s Lifespan Longer than Storage Tanks?

There are several reasons tankless water heaters last almost twice as long as conventional storage tank water heaters. There is less sediment buildup, which leads to less corrosion, fewer leaks, and no risk of explosion, to name a few.

Let’s dive into those in a bit more detail. 

Less Corrosion

Corrosion is one of the biggest problems with storage tanks because it weakens the integrity of the tank. It can also cause the tank to leak. When you install a tankless water heater, you don’t have to worry so much about corrosion.

In fact, many manufacturers claim that their tankless models are immune to corrosion. This may be true because the heating element is located outside of the tank. The only thing that comes into contact with the water is the coil. This means that the heating element won’t corrode like the metal tank would.

Less sediment buildup

Sediment buildup occurs from the minerals in the water reacting with the metal parts of your water heater. A traditional water heater’s tank is made of steel, so sediment buildup is inevitable over time. This causes rusting and eventually leaks, which in turn, shortens the lifespan of your water heater. 

On a tankless water heater, there is less metal for the water to react with and less sediment buildup overall. 

Buildup can be slowed/prevented by installing a water softener to remove extra unwanted minerals from the water and also by flushing your water heater regularly. 

Fewer leaks

When a tank storage water heater corrodes, it can cause leaking. So, naturally, with a tankless water heater, there is less risk of leakage, making them last much longer, in general, than traditional water heaters. 

Rarely, however, leakage can happen in a tankless water heater. These leaks are typically found where two pipes connect or on the bottom of the water heater where the relief valve is. 

Leaks can cause serious problems if not fixed in a timely manner, so be sure to take action swiftly if you do find one. 

No water tank, no risk of explosions

As I mentioned above, when you have a tank water heater, sediment can build up in the tank over time. This can create pressure in the tank and in rare cases, can lead to an explosion. Today’s plumbing codes require tank storage water heaters to have a pressure relief valve at the top that is designed to prevent this from happening, but it still happens occasionally.

With a tankless water heater, there’s no chance of an explosion because there’s no tank to fill with pressure.

What Can Harm a Tankless Water Heater’s Longevity?

There are several things that can harm the longevity of a tankless water heating system, including improper installation and, while less common, corrosion. Let’s take a deeper look into both instances.

Improper installation

A properly installed and maintained water heater can optimize its efficiency. An improperly installed one can not only cost you money in energy bills, it can also be dangerous and decrease the life expectancy of the unit. 

Therefore, it’s recommended to hire a professional plumber and HVAC technician to install your water heater. 

While you might think that you could handle the job yourself, there are many things that aren’t obvious. Fuel type, climate, building codes, and safety concerns, such as the combustion of gas-fueled water heaters, all come into play when installing a water heater.

Apart from being dangerous, improper installations can cause expensive repairs, and you could also void your warranty coverage.

If you still want to install it yourself, make sure you read through the manufacturer’s manual thoroughly before attempting it. Also make sure to get any necessary permits required by your city.


Now, as I mentioned above, your tankless water heater won’t be at as much risk for corrosion as a tank storage water heater for the mere fact that it does not have a large steel tank with sitting water.

However, the system is not immune to corrosion. In fact, anything with water running through it is at risk of some kind of corrosion.

Since tankless water heaters are so small, even the tiniest leak could cause problems. Not to mention, gas-powered tankless heaters are susceptible to condensation drips onto the burner, which could cause the metal parts inside the burner to rust.

The best way to prevent corrosion and stop it from taking years off the life of your water heater is to regularly inspect the unit for leaks and contact a professional to repair them right away.

Cost of repair

For most repairs on tankless water heaters, you will have to pay a professional who will charge you for labor costs. The price of repairing a tankless unit depends on how old it is and how big the problem is.

According to Angie’s list, the cost to repair a tankless water heater is, on average, $587, with typical costs falling somewhere between $220 and $956. You should be able to get estimates from several companies before deciding which company to hire. 

You can save on repair costs by keeping your water heater running smoothly with routine maintenance. I’ll touch a bit more on that below. 

How to Extend Your Tankless Water Heater’s Lifespan

The best way to extend the lifespan of your tankless water heater is to keep up with maintenance. 

Even though a tankless water heater does not have a tank, there is still a chance that minerals can build up on the inside of your water heater’s heating chamber. So proper maintenance requires that you flush out those minerals at least once a year. This process is known as descaling.

Next, I’ll walk you through the steps on descaling your tankless water heater.

Steps to Descale Your Water Heater

When you are unsure about handling this yourself, it’s always best to call in a professional. But for you DIYers, I’ll walk you through how to properly descale your tankless water heater.

You will need a descaling pump, a large bucket, two drain hoses, and 3-4 gallons of food-grade white vinegar.

1. Turn the power off of your heater 

This is a very important step that you don’t want to miss. Trying to descale a water heater that still has electricity running through it can cause irreversible damage to the unit.

You can turn gas water heaters off by turning off the gas valve. For electric water heaters, turn off the circuit breaker, and then remove the cover plate and test the wires inside with an electrical tester. Once you’ve ensured there is no electricity left running through the unit, continue on to step 2. 

2. Shut off the water supply valves

They will most likely be located underneath the water heater. Make sure to turn off both hot and cold water supply valves. 

3. Connect the hoses

Before connecting the hoses and descaling the pump, make sure the pump is unplugged. Attach the first drain hose to the cold water value connecting the other end to the pump and the second hose to the hot water valve with its other end in the bucket.

Make sure everything is connected nice and tight, and put the pump in your bucket.

4. Pour vinegar into the bucket

Now pour the vinegar into the bucket, completely covering the pump. About 3-4 gallons of vinegar should do the trick!

5. Start descaling

Now that you’re all set up, you are ready to start the descaling process. All you have to do now is turn on the hot water valve and the pump and let it go to work. The whole process should take about an hour so you can sit back and relax until it is finished. 

After about an hour, turn off the pump and let the vinegar flush back out.

6. Rinse the heater with water

Now that you have descaled the heater with vinegar, you’ll need to rinse it. Take off the hose that is attached to the cold water valve and the pump, but keep the hose that is on the hot water valve connected. Replace the service valve cap and turn on the cold water. Water should start flowing through the water heater, and let it drain into the bucket until it’s full. 

7. Let there be hot water!

You did it! You descaled your water heater. Now disconnect all the hoses and put everything back to where it was. Turn your water heater back on and check that everything is working properly. 

Warranty on Tankless Water Heaters

There are many different types of warranties for tankless water heaters, so it’s important to understand which one applies to the unit you have or are thinking about buying. The warranty will vary based on the manufacturer, as well as the type of installation.

Most manufacturers offer warranty coverage for the heat exchanger for ten years and the rest of the components for three to five years. Some even offer a lifetime warranty. If you want to make sure yours lasts longer, look for those types of guarantees.


In conclusion, tankless water heaters are a great choice for homeowners who want to save money without sacrificing comfort. Even though you may find yourself paying more upfront for some models (like condensing tankless water heaters), when you factor in the savings you will get from its efficiency and the additional time you will get to use it, it will end up saving you money in the long run. 

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