How to Fix Water Hammer (Banging Pipes)

Water hammer is the loud banging or hammering sound in pipes that occurs when the flow of water is suddenly stopped or forced to change direction. While it can sometimes be a minor annoyance, severe cases can damage fittings, joints, and even lead to burst pipes. This guide provides a step-by-step diagnostic to assess your risk and offers proven DIY fixes you can implement immediately to solve the problem and protect your plumbing.

Use this checklist to determine the severity of your issue. Check all that apply:

• The banging is extremely loud and violent
• The pipes are visibly shaking or moving
• The noise occurs at multiple taps and appliances (not just one)
• You have recently noticed new leaks or moisture around pipe joints
• Your home has older plumbing (e.g., galvanised or polybutylene pipes)

• If you checked 2 or more boxes: This indicates a high-risk situation. We strongly recommend you call a licensed plumber today to prevent potential damage.
• If you checked 1 box: Proceed with caution. Try the simple DIY fixes below, but monitor the situation closely.
• If you checked 0 boxes: Your issue is likely safe to address with the following DIY methods.

• High-Risk: Turn off the water to the affected appliance if possible and call a professional
• Low-Risk: Proceed to Section 3 to try the easiest fix now

For moderate noise isolated to one or two areas, a DIY fix is often successful. For widespread, severe banging, or if you’re not comfortable with basic plumbing tasks, a professional is the safest and most effective choice.

Best for DIY: You’re dealing with a recent, moderate noise, and are comfortable shutting off your main water supply.

Best for a Plumber: The banging is severe, you have older pipes, you’ve already tried DIY fixes without success, or you suspect a leak.

This simple, 20-minute procedure restores the air cushions in your plumbing that are designed to absorb water shock. It requires no special tools and is the most common solution for water hammer that appears suddenly.

1. Shut Off the Main Water Valve: Locate your home’s main water shutoff valve (often in the laundry, garage, or outside near the water meter) and turn it completely off.
2. Open Highest Tap: Go to the top floor of your home and turn on a tap (both hot and cold).
3. Open Lowest Tap: Go to the lowest point in your home (laundry sink or outdoor tap) and open it.
4. Drain the System: Let all water drain out of the pipes. You’ll hear it sputter and stop. This allows the air chambers to refill with air.
5. Close the Lowest Tap: Once the water has stopped draining, close the lowest tap tightly.
6. Slowly Turn Water Back On: Go back to the main valve and turn it back on SLOWLY to prevent another pressure surge.
7. Bleed the Air: Air will sputter from the top-floor tap you left open. Once it runs smoothly, turn it off. Go around your house and turn on other taps briefly to bleed any remaining air.

Try This Now: This should be the very first thing you try. If the banging goes away but returns after a few weeks, it means your system relies on air chambers and you may need a more permanent solution like an arrestor.

Pipes that aren’t properly secured can move when water pressure changes, amplifying the water hammer effect. This fix involves finding and securing these loose sections.

1. Locate the Problem Area: Have someone turn taps on and off while you listen for the source of the noise.
2. Access the Pipes: Check exposed pipes in the ceiling cavity, under the house, or in the garage.
3. Install Pipe Clips: Use proper pipe clips or straps (available at Bunnings for about $2-5 each) to secure pipes to joists or walls every 1-2 metres.
4. Add Padding: For pipes that pass through walls or joists, wrap them with foam pipe insulation to prevent direct contact.

Common Mistakes: Don’t overtighten clips as pipes need room to expand and contract with temperature changes.

Water hammer arrestors are sealed air chambers that won’t lose their effectiveness over time. They’re particularly effective for washing machines and dishwashers.

1. Purchase the Right Arrestor: Buy a screw-on mini arrestor from your local hardware store ($20-40 each). Look for ones rated for residential use.
2. Turn Off Water Supply: Shut off the water to your washing machine or dishwasher.
3. Disconnect the Hose: Unscrew the supply hose from the tap or appliance.
4. Install the Arrestor: Screw the arrestor onto the tap, then reconnect the hose to the arrestor.
5. Test the System: Turn the water back on and run a cycle to ensure the banging has stopped.

Resource Specifications: For washing machines, choose arrestors rated at least 150 PSI. Sioux Chief and Oatey make reliable models available in Australia.

Water hammer (or hydraulic shock) is a high-pressure shockwave created when a large amount of moving water is forced to stop abruptly. This momentum transfer creates a wave that travels back through the pipes, causing the “hammering” sound as the pipe vibrates and strikes surrounding structures.
Think of it like a freight train hitting a wall – all that momentum has to go somewhere, and in your pipes, it becomes a pressure wave that rattles through the system.

Key Takeaway: The main causes are high water pressure, failing air chambers, or quick-closing valves found in modern appliances like washing machines and dishwashers.

This is why you often hear the noise when a washing machine stops filling or you turn a single-lever mixer tap off quickly.

1. Check Your Home’s Water Pressure: Buy a simple pressure gauge ($15 at Bunnings) that screws onto a garden tap. Ideal pressure is between 275-415 kPa (40-60 PSI). If it’s over 550 kPa (80 PSI), consider installing a Pressure Reducing Valve (PRV)and other ways to prevent water leaks.
2. Install Arrestors on Key Appliances: Proactively install mini-arrestors on your washing machine, as it’s the most common culprit.
3. Turn Taps Off Gently: Avoid slamming single-lever mixer taps off quickly. A gradual turn-off gives the water time to slow down naturally.
4. Regular Maintenance: If your home relies on air chambers, reset them annually as preventive maintenance.

Don’t hesitate to call a licensed plumber from North East Plumbing if:

• The banging persists after trying these fixes
• You notice any signs of leaking or water damage
• The problem affects multiple areas simultaneously
• You’re not confident working with your home’s plumbing

Remember, while water hammer might seem like just an annoying noise, ignoring severe cases can lead to costly repairs down the track. Taking action now – whether DIY or professional – will protect your home and give you peace of mind.