Replacing a water heater before it completely fails is a smart thing. Not only will a ruptured water heater cause destruction of property, it can also injure or end human life if it explodes badly.
So, how long can a water heater last? Or how do you know it’s time to replace your old water heater?
On average, a water heater will last for 12 years. This however depends on the brand, water quality, maintenance practices and installation location among other factors. Electric water heaters last longer than gas water heaters, while tankless water heaters will last even longer.
A water heater can even last for 20 years, but it is risky to have it for that long. In case the water heater bursts or even develops a leak, it can cause costly water damages or injuries especially if it is installed in places like the attic or basement.
A water heater that is more than 10 years old, makes knocking/popping sounds, produces rusty water, is leaking, the hot water is hardly enough or whose water is not hot enough needs to be replaced. Poorly maintained water heaters will need a replacement before they are even 10 years old
Electric water heaters will last for 10 to 15 years while gas water heaters will last for 6 to 10 years. Again, this will depend on brand, water quality, maintenance practices and the installation location. Tankless water heaters will last for up to 20 years or more.
The size of a water heater does not affect how long it lasts. A 40-gallon water heater will last for as long as a 50-gallon water heater provided they are maintained the same, are of the same brand, are installed in the same location and are of the same type (gas/electric).
Factors Affecting How Long a Water Heater Lasts
Here are the things that affect how long your water heater will last:
1. Installation Location
If you touch your water heater tank, you will notice that it is quite hot. In essence, the water inside the tank is losing its heat to the surrounding environment.
Picture a water heater installed in the garage and another in the attic or basement. It goes without saying that the garage is way cooler than the basement or attic.
What happens in such a situation is that the water heater in the garage will lose more heat to the surrounding air than the one in the basement or attic. As such, the water heater in the garage will need to be on for longer, which accelerates its wear and tear.
The advantage of having your water heater in the garage is that there is reduced risk of property damage should it rupture or start leaking, than a water heater in the attic or basement.
You can therefore hold on to your water heater past its 10 year anniversary (recommended replacement date) as long as it is working great.
2. Type of Water Heater
Tankless or on-demand water heaters last longer, followed by electric water heaters then gas water heaters come in last. All of these water heaters have their advantages and disadvantages but in as far as longevity is concerned tankless water heaters are the clear winners.
Tankless water heaters are only on where there is a hot water demand in the house. This reduces their wear and tear significantly. They also have fewer parts compared to tank-type water heaters, which means fewer repairs and an overall high lifespan.
When it comes to tank-type water heaters, electric water heaters will last longer than gas electric water heaters. Unlike gas water heaters where the burner is always on, the heating elements in electric water heaters are turned on and off by a thermostat when the water temperature goes down.
With the gas water heaters, the tank is always being subjected to heat (which means constant expansion). This causes them to wear out quicker than their electric counterparts.
Needless to say, the quality of a water heater will depend how long it is going to last. Some brands are simply better than others.
As is the case with all things, some of the best brands tends to be some of the expensive as well. Quality is not cheap.
Some of the best water heater brands are:
- A.O. Smith
- Bradford White
- Rinnai (tankless)
Any of the above water heaters will be worth your money, especially the first 2.
4. Water Heater Size
I mentioned earlier that the size of a water heater does not matter in as far as longevity is concerned. That is assuming all factors are held constant, including and most importantly sizing.
A water heater needs to be properly sized in accordance to your household size and its hot water demands. In this case, bigger is always better than smaller, though not economical.
A small water heater relative to the hot water demands in the house means that the water will need to continuously be heated. The more the tank is heated and cooled (by cold water) the more it expands and contracts rapidly, subjecting it to stress and shortening its lifespan.
5. Water Quality
Water heaters in areas with hard water will last for fewer years than water heaters in area with fresh water. The minerals in the water accelerate the wearing out of the water heater’s inner lining, which exposes the tank to corrosion.
Mineral deposits present in the water (especially lime/calcium) will settle at the bottom of the tank forming sediment. The sediment starts eating away the tank, and that is why you will find out that most water heaters will start leaking from the bottom after a few years.
A water heater leaking from the bottom as a result of a hole created by the sediment will need to be replaced immediately.
Not only does sediment corrode a water heater but they also reduce the tank’s capacity. If 10% of the tank is occupied by sediment, a 50-gallon water heater will have been converted into a 40-gallon water heater.
6. Maintenance Practices
For a water heater to last long, it needs to be well maintained. 2 of the best ways to make sure your water heater lasts long is by replacing the anode rod and flushing it at least once a year.
The good thing is that for both of this tasks you do not need to call in a plumber. You can easily flush a water heater as well as replace the anode rod.
How to Make your Water Heater Last Long
There are things you can do to make your water heater last for more years than the average water heater. They include:
1. Size it Properly
This should happen before you even buy the water heater. A question most homeowners usually ask before buying a water heater is “What size of water heater should I buy”?
That is a good question to ask yourself prior to making the purchase. An undersized water heater will be under constant expansion and contraction which weakens it.
Apart from that, a small water heater means that the last member of the family to take a shower in the morning will hardly ever have hot water.
Sizing a water heater needs a bit of calculation, to determine your household’s peak hot water demands. With that information, you will be in a position to buy a properly sized water that will last long as well.
I have written a detailed separate post on how to size a water heater. Read it here.
2. Flush it Yearly
As I have already mentioned, sediment will settle at the bottom of your water heater and start to corrode and eat it away. A good way to prevent that from happen is flushing out the sediment from your water heater.
There is a difference between flushing and just draining a water heater. While flushing the water heater, you will try to use the pressure of the cold water to agitate the sediment in the empty tank and flush it out.
Now, if you have not flushed your water heater in 4/5 years since you bought it, you will have little success trying to flush it at the moment. The sediment will have already hardened at the bottom of the tank and will just not come out.
The importance of flushing a water heater also prevents heating elements from shorting and burning, and also improves the overall efficiency of the water heater. You will also have enough hot water since the capacity of the tank is maintained.
If you ever hear popping or knocking sounds in your water heater, you have sediment in there than needs to be flushed out.
I have written a detailed article on how to flush a water heater. Read it here.
3. Replace the Anode Rod
If you look at the top of your water heater, you will see a plug next to the water connection pipes. That is the anode rod connection.
A water heater anode rods runs from the top to the bottom of the water heater tank. Water heater manufacturers recommend that you replace the anode rod after every 3-5 years, which can double the life of the water heater.
These rods, which are usually made of less noble metals like magnesium or aluminum are installed for sacrificial purposes. They sacrifice their lives for that of the water heater, and that is how the water heater is able to last long.
Elements in the water opt to react with the anode rod instead of the water heater inner lining, since these elements will readily give away their electrons. For this reason, they (anode rods) tend to wear out faster and hence the need to replace them.
When you fail to replace your water heater anode rod and it is completely eaten away, the elements will turn to the water heater and start to eat it away.
I have written a separate article on how to replace a water heater anode rod. Read it here.
4. Install a Thermal Expansion Tank
If you do not already have one, a water heater thermal expansion tank is a very useful piece of equipment for your safety, and for increasing the life of your water heater.
It is a small tank (about 2-gallons in volume) that is installed on your water heater’s cold water supply line with the help of a tee. The tank has 2 sections.
At the bottom of the tank is cold water while the top half is compressed air separated by a diaphragm. When the water in the tank is heated and it starts to expands, the extra pressure is accommodated by the thermal expansion tank.
This relieves the pressure from the tank meaning it is not under stress. Remember that the pressure buildup in the tank and expansion is what causes the tank to weaken and fail.
A water heater thermal expansion tank especially makes sense if your plumbing has a closed loop. This is usually due to installation of a check valve or pressure reducing valve, meaning the water in the tank has nowhere to expand to.
I have written a detailed article on everything you may want to know about water heater thermal expansion tanks. Read it here.
5. Adjust the Water Heater Temperature
It goes without saying that the more you heat water, the more it expands. And the one thing we know about hot and expanding water is that it will exert pressure in the container it is held.
A good way to make sure that the hot water inside your water heater is not exerting too much pressure in the tank is by adjusting the temperature of the water to an ideal temperature.
The ideal temperature setting of a water heater is 120 degrees Fahrenheit. Adjusting your gas water heater temperature is quite easy, but the same cannot be said about electric water heaters.
I have therefore written an article on the same as well. Find it here.
Signs You Need to Replace Your Water Heater
The following are the telltale signs that your water heater has seen better days, and a replacement is the best option:
- A water heater that is more than 10 years old. If your water heater is 10 years or older, you should consider replacing it before it fails. This especially makes sense if it is in sensitive location where it can cause expensive water damage should it fail.
- It is not heating water anymore. Sometimes a water that is not heating water can be fixed but if the said water heater is too old, a replacement is the best thing to consider.
- The hot water is not hot enough. When the hot water is not hot enough, it could be caused by fixable things or build of sediment which inhibit the heating process. In this case, just go ahead and buy a new one.
- Knocking and popping sounds. Knocking and popping sounds from a water heater are a sign of sediment build up. This is usually impossible to flush out, and you should start planning for a replacement.
- Rust in hot water. Rusty hot water almost always indicates corrosion and sediment build up in the water heater. When such is the case and the water heater is quite old, a replacement will be the only good solution.