Home DIY and Improvement

Why Is My Hot Water System Making Strange Noises?

Why Is My Hot Water System Making Strange Noises?


The hot water system is a vital part of your home, and it’s important to recognise when something is wrong. If your hot water system is not old but makes strange noises, it may be an indication that there is a problem. You can fix some noises yourself, but others may need to be addressed by a qualified plumber.

Let’s discuss some of the hot water system noises you should be aware of.

Common Noises Made by Hot Water Systems

It is essential to correctly identify the noise from your water heater so that you can describe the noise to the plumber to help him identify the problem quickly.

These are some common noises:

  • Humming
  • Knocking or hammering
  • Gurgling, cracking, or popping
  • Screeching or screaming
  • Kicking or tapping
  • Bubbling

Humming Noises

There are many potential causes of humming sounds in a hot water system. One of the most common is mineral build-up on heating elements, which causes them to vibrate and create a humming noise. Another common cause of humming noises in hot water systems is a loose connection. A pipe or fitting can vibrate and create a humming noise if it is not securely attached.

Knocking or Hammering Noises

The knocking or hammering sound from your hot water system can be annoying, even though it is not a major cause for concern. When a tap or valve is opened, water gushes through the plumbing system causing vibrations in the pipes. Another possible reason could be the normal expansion and contraction of the metal tank when your water is heating.

However, if you notice excessive knocking or hammering sounds, it could indicate sediment build-up or corrosion in your hot water system. The sound is created when steam bubbles escape these sediments.  You may need to flush the sediments from your hot water system and, if the sound continues, have a plumber check the gas valve or thermostat.

Gurgling, Cracking, or Popping Noises

Gurgling, popping, or cracking sounds from your hot water system indicate sediment and scale build-up in the bottom of your hot water tank. This causes water to force its way through the layers. When water is boiling at the bottom of the tank, sediment rolls around, causing the popping sounds you hear. Drain residue from the bottom of the tank regularly to stop these noises.

Screeching or Screaming Noises

Do you hear a high-pitched sound from your hot water system? Well, there could be too much pressure within the tank. A stuck or faulty pressure valve causes pressure build-up and, if left untreated, can result in leaks, cracks, and worse – the tank could explode. 

Another reason for the screeching or screaming sounds could be sediment accumulation at the bottom of the tank. The sound you hear is caused by the water heating system working harder to reheat the water as the sediment builds up. To fix screeching or screaming noises, you may need to replace the pressure valve or drain the sediment. 

Kicking or Tapping Noises

Like screeching noises, tapping or kicking noises may indicate that your valves are faulty and need adjustment or replacement. It could also mean you have residue build-up in your water tank. 


A bubbling or gurgling noise from your water system means residue build-up. Calcium, lime, and other sediments from hard water gradually accumulate in the tank.

These sediments form a crust over the water-settling areas in the water tank, and when the bubbles break through the deposits, they create noise. 

Strange noises coming from your hot water system can be worrying. With the help of a trusted plumber, you are assured of a well-maintained hot water system. 

Even handy homeowners should avoid trying to address noises coming from their hot water systems on their own since there is potential for gas leaks, flooding, or scalding. Get help from a trusted plumber who will help you determine and address the cause of the noises.


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