How to Fix Water Hammer in Pipes

Water hammer is the loud banging or thudding sound your pipes make when water flow is suddenly stopped — like when a washing machine valve closes or you quickly turn off a faucet. It's not just annoying — repeated water hammer can loosen pipe joints and cause leaks over time.

What Causes Water Hammer

When water flowing through a pipe is suddenly stopped, the momentum of the moving water has to go somewhere. It slams into the closed valve and sends a pressure wave back through the pipe — causing the banging sound and pipe movement.

Water hammer is most common with:

Washing machines (solenoid valves close very fast)
Dishwashers
Quickly closed faucets
Toilet fill valves

Fix 1: Install Water Hammer Arrestors (Best Fix)

A water hammer arrestor is a device with a sealed air chamber and piston that absorbs the pressure wave when water stops suddenly.

👉 Water hammer arrestors for washing machine — 2-pack, 3/4 inch swivel connections. Install directly on the hot and cold supply hoses behind the washing machine — no tools needed, just hand-tighten.

How to install on a washing machine:

Turn off the water supply valves behind the washing machine
Disconnect the hot and cold supply hoses from the wall valves
Thread the arrestors onto the wall valves
Reconnect the supply hoses to the arrestors
Turn water back on and run a wash cycle to test

For other locations (under sinks, near dishwashers), install arrestors at the supply valve closest to the noisy pipe.

Fix 2: Reduce Water Pressure

High water pressure amplifies water hammer significantly. If your pressure is above 80 PSI, reducing it will reduce or eliminate the banging:

Test with a water pressure gauge
Adjust the PRV to bring pressure to 50–60 PSI — see our guide on How to Fix High Water Pressure

Fix 3: Secure Loose Pipes

If pipes are not properly secured, water hammer causes them to bang against framing or other pipes. Add pipe straps or cushioned pipe clamps to secure any loose sections.

Fix 4: Recharge Air Chambers (Older Homes)

Older homes may have air chambers — vertical pipe sections near fixtures that act as shock absorbers. Over time, water fills these chambers and they lose effectiveness.

To recharge:

Turn off the main water supply
Open all faucets in the house to drain the pipes completely
Close all faucets
Turn the main water back on slowly
The air chambers will refill with air as water pressure is restored

Bottom Line

The fastest fix for water hammer is installing water hammer arrestors at the source — especially behind the washing machine. It takes 10 minutes and requires no tools. Also check your water pressure — reducing high pressure eliminates water hammer in many cases.

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