Water hammer
Pipes aren't meant to bang, rattle or vibrate. Learn more on what you can do to fix this.
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What is water hammer?
Water hammer happens when flowing water is forced to stop or change direction suddenly. When that happens, the water sends a shockwave through the pipe and that shockwave can make the pipe bang, rattle or vibrate. You’ll often hear it when a tap is turned off, an appliance stops filling, or something inside the pipe blocks the flow.
What to check before calling a plumber
Those loud bangs can be worrying, but a few quick checks at home can help you work out what’s going on and resolve it.
Pay attention to what you were using when you heard the bang. It might be:
- A tap being turned off quickly
- A washing machine or dishwasher finishing a cycle
- A toilet after it refills
- An outdoor tap
This helps narrow down where the problem might be.
Water hammer often happens when water flow stops too fast. Try turning taps off slowly, or choosing “soft close” or “slow fill” settings on appliances if they have them. If the noise eases, the quick turn off may be the cause.
Check under sinks, in cupboards or along outside walls. Look for:
- Pipes that move or shake when water is running
- Pipes sitting close together
- Loose or missing brackets
Securing loose pipes can make a big difference.
High pressure is a common trigger. You might notice:
- Very strong flow from taps
- Noisy pipes when more than one tap is on
- A pressure gauge showing high levels
If you suspect high pressure, a plumber can test and adjust it.
Some older homes have air chambers that help absorb shock. Over time, they can fill with water. To reset them:
- Turn off your main water supply
- Turn all taps on to drain the system
- Turn all taps off again
- Turn your main water supply back on slowly
If air chambers were the issue, this can help reduce the banging.
Washing machines, dishwashers and fridges with ice makers turn water off instantly, which can trigger water hammer. Try:
- Checking hoses for kinks
- Making sure the appliance tap is fully open
- Running a different cycle
If the noise only happens with one appliance, it may need a pressure adjustment or installation check.
If the noise started after a renovation, new appliance or tap replacement, something may have been installed incorrectly or may be turning water off too quickly.
When to call a plumber
It’s best to get a licensed plumber involved if:
- The noise is getting louder or more frequent
- Pipes are visibly shaking
- You see leaks, moisture or corrosion
- More than one area of your home is affected
- Your water pressure seems very high
A plumber can pinpoint the cause and recommend long‑term fixes.
If South East Water assets are involved
Sometimes the cause isn’t inside your home. If your plumber believes the noise is coming from South East Water’s assets, we’ll need some details so we can investigate properly.
Ask your plumber to fill out the Water Hammer Checklist. This helps our technical teams understand what’s happening and check the right part of our network.
Send us the checklist
Once it’s filled out, email it to faults@sew.com.au with the subject "Water Hammer [Property address]."
This gives us what we need to look into the issue and work out whether our assets are contributing to the water hammer.