If you hear a loud bang or thud from your pipes every time you turn off a tap or your washing machine stops filling, you’re experiencing water hammer. It’s one of the most common plumbing noises — and it shouldn’t be ignored.

What Is Water Hammer?

Water hammer (also called hydraulic shock) occurs when water flowing through a pipe is suddenly stopped. The momentum of the moving water has nowhere to go, creating a shockwave that travels through the pipe and produces that distinctive banging sound.

Think of it like slamming the brakes in a car — everything lurches forward with force.

What Causes Water Hammer?

Quick-Closing Valves

Modern appliances like washing machines and dishwashers use solenoid valves that snap shut almost instantly. This sudden stop creates the most intense water hammer.

High Water Pressure

Excessive water pressure means water is moving faster through your pipes, creating a bigger shockwave when stopped. Melbourne homes in some areas can have pressure well above the standard 500 kPa.

Loose Pipes

Pipes that aren’t properly secured to walls or joists will move and rattle when water hammer occurs, amplifying the noise.

Failed Arrestors

Many homes have water hammer arrestors (small air chambers) already installed. Over time, these can become waterlogged and lose their cushioning effect.

Worn Stop Valves

Old tap washers and valves that don’t close smoothly can create mini water hammer effects.

Why You Shouldn’t Ignore It

Water hammer isn’t just noisy — it can cause real damage:

• Pipe joint failure — Repeated shockwaves loosen connections and cause leaks
• Burst pipes — In severe cases, the pressure spike can rupture pipes
• Appliance damage — Washing machines and dishwashers can suffer valve damage
• Fitting damage — Taps, mixers, and connections wear out faster
• Water damage — Any of the above can lead to flooding

DIY Fixes to Try

1. Check Your Water Pressure

If you have a pressure gauge, check your mains pressure. Anything above 500 kPa is too high for residential plumbing. A plumber can install a pressure limiting valve to bring it down.

2. Secure Loose Pipes

If you can access the banging pipe (in a ceiling cavity, under the floor, or in a wall cavity), add pipe clips or foam insulation to stop it moving.

3. Drain the Air Chambers

If your home has air chambers (short vertical pipes near taps):

1. Turn off the main water supply
2. Open all taps in the house (start from the highest point)
3. Let all water drain out completely
4. Close all taps
5. Turn the water back on slowly

This refills the air chambers with air, restoring their cushioning effect.

4. Turn Taps Off Slowly

A temporary fix — turning taps off gradually rather than quickly reduces the shockwave. But this doesn’t address the root cause.

When to Call a Plumber

Get professional help if:

• Water hammer is severe or getting worse
• DIY fixes haven’t solved the problem
• You can’t locate the source of the banging
• You notice leaks after water hammer occurs
• The noise happens with washing machine or dishwasher use
• Your water pressure seems unusually high

Professional Solutions

A plumber can fix water hammer with:

• Water hammer arrestors — Small devices installed near problem valves that absorb the shockwave
• Pressure limiting valve — Reduces mains pressure to a safe level
• Pipe securing — Properly clipping and bracing pipes to prevent movement
• Valve replacement — Installing slower-closing valves where needed
• Mini expansion vessel — Absorbs pressure surges in the system

Stop the Banging

If your pipes are banging every time you turn off a tap, don’t wait for a pipe to burst. Hankook Plumbing can diagnose and fix water hammer across Melbourne’s eastern suburbs.

Call 0407 756 172 to book a plumber.