Can a hot water heaters explode? The best answer

You might hear a banging sound in your water heater. This can be quite scary and you might wonder if it can explode. The good news is that it probably won’t. In my career, I have never seen it happen.  The banging can be caused by air or dirt in your system. While it is possible that this leads to an explosion, it doesn’t happen often and is a rare occurrence as multiple things must fail at the same time.

New systems have a lot of sensors and shut off automatically if they notice that something is wrong. There is an advanced computer in new water heaters that controls the whole process. In doubt, the system shuts down or gives an alarm.


For example, if the sensors notice that the air exhaust is coming back into the system, it will cause an alert and the system will shut down. If there is a problem with the flames, the system will shut down as well. It is always possible that the sensors don’t function properly and that the system gets in trouble. Often there is redundancy and another set of sensors but cheaper systems might not have these. Older systems didn’t have these safeties and were more prone to exploding. 

One cause can be an overheating water tank where the pressure relief valve malfunctions. The hot water and steam have nowhere to go and the tank can explode. 2 or more things have to be broken at the same time on your water heater for this to happen. The chance that this happens is therefore quite low.

Electric water heater: do they explode?

There can be a short circuit in a water heater on electricity. Normally the system should turn off and there shouldn’t be a problem. It is always possible that something leads to a fire or explosion. For this reason, you shouldn’t have burnable items close by the heater. These are edge cases though and modern systems are very safe if they are properly installed and maintained. 

Gas heater: chances of exploding

Water heaters that work on natural gas need a constant stream of gas to function properly. This gas can leak and explode if it builds up and gets in contact with a heat source. A smell is added to the gas to make sure that a gas leak is noticeable. You shut off the gas immediately if you smell gas. This is done by turning a valve where the gas line enters your house.

Don’t panic when you smell it as there needs to be a lot of gas before it can explode. The smell will have to be terrible before an explosion is possible but you shouldn’t take risks with it anyway. You can call a plumber or your gas supplier to see what needs to be repaired. 

A bigger danger than an explosion is the buildup of CO2. This gas can be released when the system doesn’t vent the exhaust gasses properly. A lot of cities require that you have sensors for this in the house as it is possible that things don’t turn out well if you have a lot of CO2 buildups. This gas is invisible and odorless and can surprise people. You should let your system get cleaned every 2 years to make sure that it works properly and doesn’t leak CO2. 

Hot water heater explosion

While it doesn’t happen often, water heaters can go out with a bang. It can destroy a room or a house:

You can call your plumber or turn your system off if you really feel that the water heater is making too much noise. In most instances, it won’t be a problem and the system just needs some maintenance. You have to get it looked after but it probably won’t explode. It can get damaged though if the system makes noise for a while. There are other reasons why you have to maintain your system.

For example, if the sacrificial anode rod breaks, it can affect your tank and even your pipes! Sediment buildup such as chalk can also be an issue. Once again, your system should stop by itself. It often takes one hour or more to properly open and clean a system.

Some plumbers are lazy and don’t maintain the whole system. If they leave after 10 minutes, it can indicate that the plumber didn’t do a proper job. Every 2 years the system should be checked. Some systems just don’t get dirty as they used advanced systems.

Still, the plumber can use additional sensors to see if it is burning clean and that there are no other issues. They can also check for cracks or other issues that can lead to big problems. 

Some people still have a system that is older than 10 years and these water heaters are less advanced and don’t have a lot of sensors. These are more prone to issues. If they are maintained well, there shouldn’t be too much of a problem though.

It is hard to tell when a water heater will break. Some do so after a few months whereas others can last for decades. There are a lot of things affecting this, from usage, and manufacturing errors to the cleanliness of the water. 

Photo by Marian Florinel Condruz on Unsplash

Hot water heater pressure relief valve keeps opening: water pouring out

Water heaters can leak water. This is often not a good sign if it happens often as this water contains acids. It is often drained with a pipe but some people use a drain pan for this. This is another indication that your system might need some attention as the pressure is too high. If the pressure relief valve suddenly blocks, it can break your hot water heater.

Check if your water heater gives you an error code on the display. You can use the manual to see what the code means or use Google to find out. In some instances, you can lower the temperature of the system. In other cases, you will need to call a plumber to replace a part.

Explosions are often a combination of things that go wrong. If you pay attention to your system as a homeowner and check it every month to see if something weird is going on (such as water leaking from it or loud noises), the chances that your water heater will explode are very low. 

It is important to read the instructions for your water heater. When you turn it on or off, you have to follow the right procedure. If you get error codes, it is essential that you examine what is going on. Ignoring them is not going to solve the problem. Sometimes it can indicate that a part needs to be replaced or cleaned. Water heaters also have a lot of settings that can make them more efficient. 

To conclude, we can state that while water heaters can make weird noises, new systems are safe and probably won’t explode. It is best to contact a plumber when you hear these noises to check what is going on. Your system will probably shut down if there is really an issue. This can be annoying as it is hard to do the dishes or take a shower without hot water.