Water Heater Making Hissing Noise 

Inside our homes, water heaters represent a constant hot water source that we need to fulfill our everyday tasks and chores. After all, without hot water, a lot of cleaning would be much more difficult. When things go awry and the water heater starts making weird noises or functions strange, our entire way of life can be affected. This is why we should take note of strange situations before they start affecting us seriously, which is why today we are discussing the causes of water heater making hissing noise.

Why does my water heater make a hissing noise?


When it comes to our water heaters, any source of weird sounds can be a cause for concern. While sometimes these sounds signal harmless changes, there are cases where the consequences of ignoring them may be far direr. The hissing sound specifically has some associations that should be considered. [1]

  • High water heater temperature

Regarding sources of weird sounds, high water temperature is up there. This cause of hissing sounds occurs when the temperature within the water heater is too high. Of course, the heaters are made to allow them to regulate the pressure within themselves automatically.

This is done with a temperature-pressure release valve that automatically releases excess stress from the tank. As you can imagine, the higher the temperature, the higher the tank’s pressure, leading to some dangerous situations.

In addition, this valve can sometimes produce hissing noises that could cause worry. If hissing becomes worryingly frequent or goes on for a longer time, lower the water heater’s temperature.

If this is a common occurrence, check if the valve itself is operating properly. It’s not impossible that it’s experiencing malfunctions and may need to be replaced.

  • Leaks in water heater

In situations where the hissing is more frequent, even when the hot water isn’t being used, you could be dealing with a leak. Leaks in the tank could be caused by your water heater’s tank wearing out or due to physical damage. On the other hand, it’s possible that the leak happens due to the recent malfunctions of other parts of the water heater.

Regardless of the cause, leaks are a decently severe concern. While the initial side effects may only showcase as small puddles of water or excess moisture in the air, allowing this problem to persist could lead to a full-on burst water heater. Needless to say, this is the worst-case scenario.

The sheer potential for water damage this produces is troublesome enough, but it can worsen. For example, if a water heater explodes while somebody is near it, they could get burnt by hot water within it. Furthermore, the water heater parts could get propelled during the burst, resulting in serious injuries.

  • Sediment buildup

The water within our homes has the potential to carry debris and sediment with it. While these could be entirely microscopic at the beginning, they will start to build up over a long period of time. The source of sediment can be anything from dissolved minerals to impurities in the water.

Regardless of the actual materials that induce them, sediment buildups and other similar materials can lead to further problems. Completely clogging the pipe could result in devastating consequences for it.

The hissing sound may be a proper giveaway for these issues before they get out of hand. The hissing sound in this situation comes from bubbles of hot water popping on the sediment within the water heater tank and pipes.

Getting the sediments themselves cracked can be an issue if other sources of resolving this issue don’t work. Make sure to inform yourself on how to break the sediment properly.

There are other sources of these problems, but these are some of the most common ones. Keep in mind that the type of your water heater may also change the way the water heater functions as well as the issues it could have.  [2]

Gas water heater making hissing noise

rheem water heater

With gas heaters, the hissing still remains incredibly dangerous in terms of warning signs. At the same time, their style of operation may result in different side effects. This includes more gas-related problems. These may include gas escaping from the water heater as well. Gas water heaters have their own issues stemming from their operational procedure. The flammable aspect of them being only part of the issue. [3]

As far as gas water heaters go, the aforementioned issues we’ve listed are all pretty well known to them. After all, despite using gas, their performance and function are pretty standard. However, the gas water heater can still suffer from sediment buildup and other problems.

To resolve those issues, you should get a professional to look at your gas water heater. Tampering with one on your own can be pretty dangerous. Allowing the problems to develop and unfold is also not suggested because of the growing repercussions that come with it.

Hot water heater making hissing noise

The hissing noise we’ve discussed is inherent to any hot water heater, be it an electric one or a gas one. The problem will be rather apparent and become more pronounced as it ramps up.

Getting your hot water heater back into its top form is important so make sure to achieve this in the fastest possible way. Below, we will explain how you may fix this issue in certain situations. That should help with some issues and get your hot water heater back online.

How to fix water heater making noise?


There are a few ways around resolving issues with your hot water heater and it making hissing noises. While more difficult problems shouldn’t be taken care of alone, others could be easily resolved with some effort.

With the most common source of problems being buildup, we will cover that first. With all the minerals flowing through the water within our homes, it figures side effects like these would eventually occur.

The severity of this buildup may alter the ease of resolution. What’s most important to remember is that you should make sure the hot water heater is intact before risking immediate repairs.

If the internal malfunction has already damaged it, you could end up with burns or even more harmful side effects. Once you confirm that no dents or leaks are present on the hot water heater, it’s time to get down to actually resolving the issue.

The most common course of action that’s taken when repairing the hot water heater is to try and flush the tank to remove buildup. This can be done by turning off the gas valve and then shutting off the inlet water valve. This will allow you to prevent water from flowing back into the water heater tank and eliminate potential dangers of engaging with the hot water heater while gas may still be present within it.

Now you need to connect a hose to a drain valve and then release the valve. Empty the tank fully so that none of the water remains inside. This will simultaneously wash out some of the buildups. Once the tank is empty, it’s time for the next step.

It’s time to open the inlet pipe. This way, you can let a lot of the water and sediment out in an effort to drain the whole pipe. Repeat this process a few more times in order to fully flush the whole system. Finishing this flushing process should get rid of all the sediment.

In cases where the issue persists, the DIY approach may not be possible. While there are other things you could attempt, they could be dangerous, and by proving that the flushing isn’t the solution, you reinforce the possibility of there being heftier problems with the water heater.

That means contacting a professional may not only be a necessity but an urgent move to commit to. The expenses we would pay to the professionals are much smaller than the ones we’d end up with if the water heater bursts.

When using a tankless water heater, you should use a different course of action to flush it. As far as other issues go, you’ll require a different DIY solution for them which you should engage with once the problem is diagnosed. [4]

Related: Water Heater Making Noise When Water is OFF


Water heaters are an important and integral part of our homes that provide us with hot water, which is why the hissing sounds and other odd responses from them can be so harrowing to hear. As we’ve seen, that fear is well justified. Even if the worst-case scenario of a burst water heater doesn’t happen, we are still in danger of diminished functionality or outright malfunction of the hot water heater.

Thankfully, the methods of diagnosing the water heater aren’t too convoluted and can be done on your lonesome. However, no matter what sort of inspection you are conducting, make sure to stay as safe as possible with your preparations as well as the execution of the check. Never leave the water heater on or water flow to it on while attempting to check it.

Flushing the water heater may be all you need, but in situations where that or other simple fixes don’t solve it, you should get help from a professional. They will quickly repair the water heater, potentially noticing other issues with it that escape the untrained eye.

We hope the guidelines and suggestions above will aid you in getting rid of potential problems. The safety of your home is paramount, so making sure no appliance poses a risk to it ends up being the most important factor in maintaining it.