You turn the kitchen or bathroom tap off and suddenly hear a bang, knock or thud from somewhere behind the wall.
In many cases, this is known as water hammer. It happens when flowing water is stopped suddenly, creating a pressure wave through the pipework. The movement can make pipes vibrate or knock against surrounding surfaces.
It can be surprising when it first happens, but the sound itself does not automatically mean you have a major plumbing problem.
What Causes Water Hammer?
The usual trigger is a tap or valve that stops the flow of water quickly.
A few things can contribute:
- Fast-closing taps or valves
- Loose or poorly supported pipework
- High water pressure
- Appliances with quickly closing valves, such as washing machines and dishwashers
The noise can also be more noticeable at certain fixtures than others.
For example, you might only hear it when the kitchen mixer is turned off, while the bathroom taps are quiet.
Why Is It Only Happening at One Tap?
If the noise happens at one particular tap, the problem may be related to that fixture or the pipework connected to it.
Pay attention to when the noise happens:
Only one tap:
The issue may be local to that fixture or its pipework.
Several taps:
The cause may be somewhere else in the home’s water supply system.
When the washing machine or dishwasher stops:
The appliance’s valve may be contributing to the noise.
This doesn’t give you a diagnosis by itself, but it can help you describe the problem when getting it checked.
What About Water Pressure?
Water pressure can play a part in noisy pipework.
Water Corporation notes that high water pressure can cause excessive noise in water pipes and may also increase the risk of leaks and bursts.
That does not mean every banging pipe is caused by high pressure. A plumber may need to check the pressure at the property along with the pipework, fittings and valves to determine what is actually causing the noise.
What If the Noise Started After Water Works?
There is another possibility if the sound only appeared after the water supply was turned off and restored.
Water Corporation says that air can enter the pipes during water supply works, which can cause a loud sound when a tap is first turned on. Running the inside taps can help clear the trapped air.
That is slightly different from the classic bang when a tap is turned off.
So it is worth noting exactly when you hear the noise.
Should You Be Worried About Banging Pipes?
An occasional noise does not necessarily mean something is about to fail.
However, it is worth getting the plumbing checked if:
- The banging is becoming louder or more frequent
- Several fixtures are causing the noise
- Pipes visibly move or vibrate
- You notice leaks around fittings or connections
- The problem started after plumbing work or changes to the water supply
Water Corporation advises that excessive pressure can contribute to pipe noise and can increase the risk of leaks and pipe bursts.
The aim is not simply to make the noise disappear. The cause needs to be identified.
What Can a Plumber Check?
There is no single fix for every case of water hammer.
Depending on the property and the symptoms, a plumber may need to check:
Water pressure
To see whether pressure at the property is contributing to the problem.
Pipework and supports
To check whether pipes are moving or vibrating when the flow stops.
Taps and valves
A fast-closing or faulty valve may be contributing to the pressure surge.
Appliance connections
Washing machines and dishwashers can also create banging when their valves close.
The right fix depends on what is actually causing the noise.
A Quick Check Before You Call a Plumber
Next time you hear the bang, take note of:
- Which tap or appliance was being used?
- Does the noise happen when turning the water off, on, or both?
- Is it one bang or several?
- Can you feel vibration through the pipework?
- Has anything recently changed with your water supply or plumbing?
That information can make it easier to work out where to start looking.
How Perth Local Plumbing & Gas Can Help
If your pipes regularly bang when taps are turned off, it is worth having the cause checked rather than simply putting up with the noise.
At Perth Local Plumbing & Gas, we can assess the plumbing, check the likely cause and explain what needs to be done before any agreed work begins.
Whether the issue is related to pressure, pipework, a fitting or a valve, the work should be based on what is actually happening at the property.
Frequently Asked Questions
1. Why do my pipes bang when I turn the tap off?
It can be caused by water hammer, where flowing water stops suddenly and creates a pressure wave through the pipework.
2.Is water hammer caused by high water pressure?
High water pressure can contribute to excessive pipe noise, but it is not the only possible cause. Pipe movement, taps, valves and appliance connections can also play a part.
3. Why do my pipes bang when the washing machine stops?
Washing machines and other appliances can have valves that close quickly, which can create water hammer and cause banging in the pipework.
4. When should I get banging pipes checked?
Have them checked with a local plumber if the noise is frequent, getting worse, affects several fixtures, or is accompanied by vibration, leaking or other plumbing problems
Final Thoughts
Don’t Ignore a Problem That Keeps Coming Back. A single bang can be nothing more than an annoying noise. But if it keeps happening, gets louder or is accompanied by vibration or leaks, it is worth finding out why.
Hearing banging pipes every time you turn a tap off? Get your Perth plumbing checked.
