When your water heater starts to make a knocking noise, it can be alarming and leave you wondering about the underlying reason and possible dangers. Understanding the causes of knocking or banging sounds coming from your water heater will help you deal with the problem successfully.

In this post, we’ll examine the typical reasons why water heaters make knocking noises and offer workable fixes to diagnose and fix the issue.

What Gives Water Heaters a Knocking Noise?

Sand accumulation in the tank:

The buildup of silt at the bottom of the water heater’s tank is one of the main reasons of banging noises. Minerals and other impurities in the water can eventually settle at the base of the tank as it is heated. The trapped air bubbles in the sediment might produce knocking or rumbling sounds when the water heater boils the water.

knocking sound in water heater

Heating and Thermal Expansion Quickly:

Thermal expansion may result from the water heater’s water heating process. It’s possible for metal parts to knock or pop when they expand and compress during heating and cooling cycles.

Hammering Water:

Another typical reason for pounding noises is water hammer. It happens when the direction or speed of the water flow suddenly changes or stops, sending shock waves through the pipes that produce loud banging noises.

Unsecured Heating Components or Pipes:

When water runs through them when the heater functions, loose heating elements or pipes inside the water heater may vibrate. The noises of clicking or knocking may result from these vibrations.

Pressure Problems

The water heater’s internal pressure changes might produce knocking noises. Loud noises can be produced and the components strained by high pressure.

Possible Solutions for the Knocking Sound

Water Heater Flushing

Regularly flushing the water heater can assist in removing trapped air bubbles and minimising knocking noises to address sediment buildup. Draining the water heater and flushing the tank can eliminate any sediment and mineral buildup. To do a proper flush, according to the manufacturer’s instructions or ask a professional for help.

Bringing Down the Temperature

Your water heater’s temperature setting can be lowered to lessen thermal expansion and the ensuing knocking sounds. Avoid lowering the temperature too much, though, as doing so could reduce the water heater’s effectiveness.

Water Hammer Arrestors Installation:

Water hammer arrestors are tools that efficiently quieten knocking noises by absorbing stress waves in the pipes. Install these arrestors at the connectors for the water heater’s inlet and outlet.

Locking Down Loose Parts:

To stop vibrations and noises, secure any loose heating elements or pipes that may be the source of the knocking.

A water pressure check:

Make sure the water heater’s water pressure is maintained within the ideal range by keeping an eye on it. Installing a pressure-reducing valve may be an option if the pressure is excessive.

When to Get Professional Assistance:

While some knocking noises are unimportant and can be eliminated by straightforward troubleshooting, some circumstances demand expert attention:

Loud and frequent knocking noises

It is preferable to have a qualified plumber thoroughly inspect the water heater if the knocking noises are very loud, frequent, or persistent. These symptoms can point to a more serious problem that needs to be addressed right now.

Age and Upkeep:

Your water heater may be more prone to developing issues, such as knocking noises, if it is old and hasn’t been properly maintained. In these situations, a professional inspection is advised to evaluate the water heater’s state and solve any problems.


Your water heater’s banging noise may be brought on by a number of things, including sediment buildup, thermal expansion, water hammer, loose parts, and pressure-related problems. While some of these problems can be quickly fixed with routine maintenance and straightforward troubleshooting, others could call for expert help.

You can ensure the effective and noise-free operation of your water heater by being aware of the possible causes of the banging noises and taking proactive steps to address them.

The lifespan of your water heater can be increased with regular maintenance, which includes flushing the water heater and fastening any loose parts. The secret to keeping a dependable and secure water heating system in your house is to take prompt action and seek professional assistance when necessary.