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May 28, 2026Hearing a loud banging noise in your Melbourne home when you turn off the tap? That’s a classic sign of a water hammer.
An arrestor might be the perfect solution to protect your pipes. We’ll explain what these devices are, how they work, if you need one, and how to install them.
Need immediate relief? Skip ahead to our guide on how to fix a water hammer. Otherwise, read this post to learn exactly how these handy devices work!
What is a Water Hammer Arrestor?
A water hammer arrestor is a small plumbing device featuring a sealed air or spring chamber that absorbs the destructive shockwave created when running water stops suddenly.
There are three main types available: piston, diaphragm, and bellows. Piston arrestors are the most common choice in Australian residential plumbing.
Plumbers prefer them because they are highly compact and incredibly durable. For added safety, the Australian plumbing standard AS/NZS 3500 recommends fitting a surge protection device on water services with quick-closing valves to protect your pipework.
Water hammer arrestor can also increase water pressure efficiency in your system. By relieving stress from your pipes, it allows a non-fluctuating and smooth water flow through your home.
How Does It Work?
Now that you know what an arrestor is, let’s look at how it functions. When running water suddenly stops or changes direction, its momentum generates a massive amount of force.
Without intervention, this force creates a violent shockwave that slams against your pipe walls.
Fortunately, an arrestor provides a safe, built-in outlet for this pressure. Inside the device is a sealed chamber containing either an air or spring mechanism.
When a fast-acting valve snaps shut and the water pressure spikes, the water pushes into this chamber, compressing the air or spring. This acts directly as a shock absorber, soaking up the excess kinetic energy and stopping the shockwave in its tracks.
The arrestor neutralizes the intense pressure surges and prevents damaging vibrations, also eliminates the loud banging sounds, which are often mistakenly blamed on trapped air in water pipes.
Instead of a destructive wave rattling your walls, the excess pressure is safely absorbed, allowing your plumbing system to settle quietly.
Do You Need a Water Hammer Arrestor?
Not every plumbing system requires an arrestor, but they are essential if your pipes are taking a beating. Look out for these telltale signs and situations to determine if you need one:
- Loud banging noises: If your pipes clang or thump every time your washing machine or dishwasher shuts off, you are actively experiencing water hammer.
- Quick-closing valves: Modern homes are full of fast-acting shut-off valves. If you frequently use mixer taps, dishwashers, or washing machines, an arrestor is highly recommended to manage the sudden water stoppage.
- High water pressure: The Australian plumbing standard AS/NZS 3500 states that residential water pressure shouldn’t exceed 500 kPa. If yours is consistently higher, the force is much more likely to cause destructive shockwaves. It’s a good idea to pressure test your plumbing to see if you need an arrestor alongside a pressure limiting valve.
- Visible damage or vibrations: Have you noticed leaking joints or pipes that physically shake? This is a major red flag that repeated pressure surges are weakening your plumbing infrastructure.
If any of these sound familiar, installing an arrestor could save you from expensive repairs.
Where Should a Water Hammer Arrestor be Installed?
Knowing where to install a water hammer arrestor in the right spot is key to solving water hammer issues effectively.
If it’s placed too far from the affected area, the device might not function optimally.
That’s why it’s essential to pressure test your plumbing system first. This will help identify areas where pressure surges are occurring so the arrestor is installed exactly where it’s needed.
These are some of the common installation points:
- Appliances that Use Water. Washing machines and dishwashers are common culprits of water hammer because they stop water flow abruptly. Installing an arrestor near these appliances can drastically reduce the issue.
- Plumbing fixtures. Fixtures like faucets, showers, and toilets can also create a water hammer. Adding an arrestor near these points can protect your entire plumbing system.
- High-Pressure Zones: If your water pressure is on the higher side, consider installing an arrestor at key junctures in your piping to ensure smooth flow.
How to Install a Water Hammer Arrestor
Before you start, it’s crucial to choose the right location. Arrestors are most effective when installed as close to the source of the shockwave as possible. The best placement locations include:
- Near the washing machine inlet valve.
- Near the dishwasher supply line.
- Near quarter-turn mixer taps in kitchens and bathrooms.
- At the main pressure-limiting valve if whole-house protection is required.
Once you’ve identified the correct spot, follow these steps to install the device:
1.Turn off the water supply
This first step is to prevent flooding. Shut off your main water supply and open a tap to drain any remaining water from the lines before you begin.
2.Attach the arrestor
Screw the water hammer arrestor onto the designated pipe or valve. Most residential arrestors use simple threaded fittings. Use plumber’s tape (Teflon tape) on the threads to ensure a watertight seal.
3.Turn the water back on
Slowly open the main water valve to restore pressure to your plumbing system. Check the newly installed fitting closely for any leaks.
4.Test the system
Run the appliance or tap that previously caused the noise and shut it off quickly. The loud banging sound should now be gone.
If you are unsure about the installation process, plumbing codes, or where exactly to place the device, don’t risk a DIY disaster. A licensed Melbourne plumber can install one quickly and safely as part of your regular plumbing maintenance.
FAQ about Water Hammer Arrestor
Let’s tackle some of the most common questions homeowners have about water hammer arrestors.
How do I know if I require a water hammer arrestor?
If your pipes make loud banging or thudding noises when you turn off a faucet or when an appliance like a washing machine finishes its cycle, you’re likely dealing with a water hammer.
This problem happens when water’s abrupt stop creates pressure surges in your pipes. Installing an anti water hammer device or a pipe hammer arrestor is a practical solution to eliminate these noises and prevent potential damage.
Why are my pipes still banging with a water hammer arrestor?
If the banging noise persists even after installing a water hammer arrestor, it might indicate that the device is no longer functioning effectively or wasn’t installed correctly.
Over time, the internal parts of the arrestor, such as air chambers or springs, may wear out.
Alternatively, the arrestor may not be positioned close enough to the source of the water hammer, or your plumbing system might need additional devices.
What is the life expectancy of a water hammer arrestor?
A well-maintained water hammer arrestor can last anywhere from 5 to 10 years. In areas with hard water, mineral buildup can shorten the lifespan of the device.
Regular maintenance and cleaning can help keep your pipe hammer arrestor in excellent condition.
Can I install a water hammer arrestor myself?
Yes, it’s a straightforward DIY job for accessible spots like behind your washing machine or dishwasher. However, if the noisy pipes are hidden inside walls or you’re unsure about your system’s pressure, it is best to leave it to the professionals.
A licensed Melbourne plumber (like us!) can handle the installation quickly and safely.
How much does a water hammer arrestor cost in Australia?
The device itself is quite affordable, typically costing between $20 and $60 at most local hardware stores. If you hire a professional, expect to pay an additional $80 to $200 for the labor. This final installation price largely depends on the complexity of the job and how easy it is to access your pipes.
What is the difference between a water hammer arrestor and a pressure-limiting valve?
An arrestor acts like a localized shock absorber to handle sudden pressure spikes when water shuts off at a specific fixture. In contrast, a pressure-limiting valve (PLV) controls the overall baseline water pressure entering your entire home from the mains.
If your household water pressure consistently exceeds the 500 kPa limit, you will likely need both devices to fully protect your plumbing.
Conclusion
A water hammer issue does not have to cause you and your family members chronic headaches. The water hammer arrestor is the ideal solution for those loud disruptive noises and will protect your plumbing system from unnecessary wear and tear.
For all of you Melbourne residents who require the installation of hammer arrestors, then please do not hesitate to contact us at Neighbourhood Plumbing!
About the Author
From unclogging the toughest drains to repairing leaking toilets, Ricky is a seasoned plumber who has brought his craftmanship to homes across Melbourne. He is passionate about sharing plumbing tips just as much as he is about fixing your plumbing issues. So, when your taps or pipes begin leaking, you know who to call.
