Informational Guide

Why Is My Water Heater Making Noise?

Some noises are innocent, but some may signal a problem. If you’ve got a water heater making noises, these are the top causes & fixes.

by Ian Haynes

"Why is my water heater making noise" is a commonly asked question. These noises could sound like anything, from a rumble to a pop or even a hum. Either way, using a loud and clunky heater can turn shower time into a nightmare.  

Some noises may signal a bigger problem. Hence, troubleshooting should take place before the issue becomes irreparable. However, does this mean that you have to replace it? Read on as we discuss.

Water heaters (especially tankless types) are expected to rumble at startup; however, those sounds are typically reasonable and shouldn't alarm users.  

The problem rears its head when you're not using hot water and still hear the noises. The most likely cause of it can be that a vacuum has been created, draining off all the water away from the unit and causing vibrations and loud noise.  

Let us look at some of the most common reasons that cause tank and tankless water heater noise. 

Build-Up Of Sediment 

At times debris may collect between the burner and the tank. Hence, when the unit starts heating, it makes a noise similar to a coffee maker. This is due to the bubbling of water when it passes the sediment layer. 

This results in hampering the quality of the tank, causing leaks that can lead to container bursting. As a result, you might have to spend a lot of money on repairs. 

How can you avoid this build-up? Flush your water heater as often as you can. If you ignore it for a while, the residue might make the flushing process impossible.  

Poor Flow Of Water 

If your hot water heater is making noise that sounds like sizzling, there is an obstruction causing an interrupted water flow.  

This problem can be traced to various valves in your unit. 

First, check the pressure and temperature relief valve. This valve releases water from the storage tank, especially in cases of excess pressure. 

Water Heater Making Noise

Every time you hear this sizzle, switch off the unit and call your local plumber for repairs. Furthermore, you can also survey the valves controlling water flow in the tank and make sure they are open.  

Continuous Change In Water Pressure 

Alternating pressure levels in the plumbing system can also cause noise in your water heater. But, again, the pipes inside your building can be the primary culprit for this. When cold or warm water passes through pipes, it slightly alters its diameter.  

Therefore, whenever the pipe grows in size, it hits against straps and wooden frames resulting in a ticking sound.  

If this happens, trace the sound where it is the loudest. When you find it, tighten your pipe; spacers can also be used to lock it in position.  

Condensations And Leaks 

One reason your water heater makes a sizzling noise is also because of the leaks in your heating unit. If your water heater is afflicted with this problem, it will likely make a sizzling sound, especially when you turn off your unit's burner.  

And if you cannot detect any leaks in the heater, search for a spot with a puddle. The best way to handle this issue is to call your local plumber.  

water heater leak
broke water heater

Fault In The Heating Element 

Another question most commonly asked is why is my water heater making a humming noise? This sound comes from the heating elements on both the bottom and top parts of the heater.  

Whenever the cold water enters the tank and moves around, the top portion will make a sound and shake.  

This humming noise is quite frustrating; however, it does not trouble the heater or any of its components. You can efficiently resolve this problem by tightening the heating element 

Water Supply Source 

And if you find yourself asking, "why is my water heater making popping noises?" know that it is likely related to the water source.  

For example, if your water heater has aluminum anode rods, it will react with higher pH level water. This reaction normally happens in houses that use chlorinated water.  

A gel covers the floor of the tank and rod whenever the chemicals combine. Therefore, you would have to remove the gel residue and change the aluminum anode to a magnesium one to fix this problem.  

Common Water Heater Noises, Their Causes & Fixes 

Even though it is not uncommon for a water heater to make noise, various sounds like knocking, tapping, humming, or screeching must be appropriately addressed to rule out the need for replacement parts or repairs.  

Let us look at the four most common noises by water heaters and how to fix them: 

Humming Noise 

If you do not flush your water heater regularly, it can cause sediment build-up to a point where it just cannot be removed via flushing anymore.  

Even though there is no cause for alarm, it shows a decrease in your heater's efficiency. At this point, you can try to flush it as much as you like. However, its drain valve is probably clogged with a layer of sediment.  

The best way to avoid this is to flush your water heater tank regularly to prevent the build-up in the first place. 

Hammering And Knocking 

If you hear your hot water heater making a knocking noise, it is probably due to the impact of water onto the shutoff valve.  

Generally known as 'water hammering,' this noise can be deafening even though; although the problem is not pressing.  

The solution is also quite simple; head on to your local hardware store and buy a water hammer arrestor. The installation is straightforward, and it will fix the sound of knocking right away.  

Screeching Or Screaming Noise 

If you're wondering, "why is my water heater making a high-pitched noise?" the most likely problem is in the check valves of your water line.  

When the check valves cannot open completely, the water is forced to squeeze through the pipes. This builds up pressure and results in a high-pitched sound.  

You can solve this by getting your water heater's check valves inspected to ensure there is no obstruction. It is better, though, to call in a professional to do that.  

Whistling Sounds 

And finally, if you're wondering, "why is my water heater making a whistling noise" it is probably malfunctioning.  

Remember, as soon as you hear this whistling noise, immediately turn off the heater. If the cause for the sound was excessive pressure, shutting it off will reduce the risk of explosion.  

It will also provide the system enough time to cool before the repair technician arrives. 

Which Water Heater Noises Are Potentially Dangerous? 

One potentially dangerous water heater noise includes whistling since it indicates pressure build-up and risk of explosion.  

Hammering or knocking also indicates a potentially serious issue, and it might not even be originating from the heater itself. You might hear these sounds when you abruptly shut access to the water to flow through the household plumbing. 

With a sudden gap in water flow, the pressure has nowhere else to go, so it returns to the direction it originated from. 

This occurrence is called water hammering. It is pretty detrimental to your home's plumbing and can even lead to a pipe burst. Furthermore, water hammering can also damage the water heater by collapsing the flue tube, expanding the tank shell, and inverting or deforming the head of the tank.  

A water hammer arrestor effectively deals with this issue.  

Reducing Ongoing Noise From Water Heaters (Long Term Solutions) 

One of the most common reasons for noise in a water heater is sediment build-up at the base, causing a popping sound.  

Let us look at the most effective ways to prevent sediment build-up and answer your question of how to reduce noise from tankless water heater.  

  • Remove at least a bucket's worth of water out of the tank quarterly to slow the build-up. The drain valve is at the tank's bottom, so use that to fill the bucket. 
  • Flushing is also an effective way to reduce noise from your water heater. Do it at least once or twice a year. 
  • Another way to eliminate build-up inside your tank is to install a water softener in your house. 

If left unchecked for a long time, it might result in rust, and you would have to replace your water heating system altogether.

Whilst installing a new water heating isn't too difficult, it's much cheaper to keep on top of maintenance.

Some other ways to reduce noise from your water heater include: 

Why Is My Water Heater Making Noise
  • Check your water heating system periodically for any parts that might have come loose 
  • Check your system for any loose straps on pipe connections 
  • Ensure that your tank's inlet and outlet valves are always open 
  • If your tankless water heater is making a vibrating noise, you must consider audio insulation  

People Also Ask (FAQs)

Can my water heater explode? 

Yes, this is possible. Anything that might cause excess pressure build-up on your water heaters, such as sediment build-up or a poor anode rod, can result in your water heater exploding.  

Can you turn off water without turning off the water heater? 

Yes, you can since there is no risk of having your water heater on with water off. The heater works on water pressure to provide hot water. Therefore, if there is no inlet pressure, there will not be any outlet pressure.  

How do turn off the power to my water heater? 

Locate your water tank and turn the power OFF by pulling the plug. Another way is to flip the circuit breaker.  

How often should you flush your water heater? 

You should flush your water heater once a year minimum.  


If you have a friend asking, "why is my water heater making a loud noise?" send them this guide. And for when you face this issue, remember, not all noises are harmful or potentially dangerous, but it is better to ascertain that everything is okay. 

Furthermore, always consult your local plumber if anything serious arises and consider upgrading your water heater if needed.

Ian Haynes is an expert writer who has successfully deployed over 500 plumbing pages and other related content. He has an excellent understanding of home plumbing issues and translates his experiences via Plumbing Lab so readers can have a better understanding of common household problems. Outside of his work, Ian likes exploring Brooklyn with his Labrador.