Banging Water Pipes: Causes & Simple Fixes

Banging water pipes can be alarming but their bark is much worse than their bite, in most cases.

The banging, knocking or, some might say, “thwacking” sound emanating from the pipes when you turn the water on may make you jump. After a while, it might just drive you crazy.

But don’t fret – the plumbing system is not just about to pack up and there is often a simple explanation and a relatively simple fix for the problem.

Before you call your plumber in a panic, take a read below and see if you can troubleshoot your issue.

The first thing to do when troubleshooting is to make a note of when the banging noise occurs. There could be several different “triggers” for the noise.

Generally, you will hear the noise when you do one of the following:

• Run the hot water
• Run the cold water
• Shut off the cold or hot water

A banging noise may also occur randomly, day or night.

The type of piping will affect your noise levels – copper pipe is generally noisier than plastic piping. Most banging pipe problems involver copper pipes.

Banging is also more common in hot water pipes than cold water ones because they expand and contract the most.

Stopping the banging noise from your pipes may involve a quick fix – or some major “surgery”. It depends on the cause and the accessibility of pipes.

Loose pipes in the wall may be the reason for the sound. The bad news is that if the pipes are all hidden behind drywall, you’re probably just going to have to live with the problem unless you’re prepared to start opening walls.

This might be an option if the noise really is driving you crazy but, of course, you will need to call the professionals for that.

The good news is that if you can see the pipes, you may be in luck.

Let’s assume that no drywall needs to be removed and the problem can be assessed from the visible water lines in your home.

Check all of the lines first. Gently push and pull visible pipes to see if they move. If any sections of pipe move when you lightly push them, mark them to come back to later.

You need to prevent water pipes from touching the surrounding building materials by providing support with every one-foot or so and at every change of direction. Also, any water line that passes through a hole should be supported.

If you’ve applied the above fix and you’re still hearing a banging noise from your water pipes, it still doesn’t mean that your plumbing system is about to pack up.

If the noise happens when a household appliance such as a washing machine or dishwasher shuts off, it could be due to water hammer.

Water hammer is a phenomenon that occurs when the flow of water in your pipes is abruptly stopped.

When the cold or hot water is shut off, the pressure resonates through the pipes, causing them to bang against anything in the vicinity, such as nearby studs, joists or other water pipes. This is the hammer sound that you hear.

Solenoid-triggered valves are often used in dishwashers, washing machines and water softeners. These shut off almost instantly and this is why these appliances are particularly associated with water hammer. Regular household faucets don’t usually don’t cause noisy pipes because the shutoff is more gradual.

Water hammer is more technically referred to as hydraulic shock. However, the loud bang or series of bangs or shuddering noises is normally more of a shock to a homeowner than the plumbing system.

Don’t panic. The sound is unlikely to damage your pipes and there is a relatively easy fix.

There are other causes of banging water pipes apart from this described above. We’ve only covered a couple of causes with simple fixes.

If your noisy water pipe problem won’t go away, it could be due to water pressure issues, sediment build-up or another reason.