Banging pipes? How to stop water hammer.
That loud bang when a faucet, toilet valve or washing machine shuts off is water hammer: moving water stopping suddenly and slamming against the pipe. It's more than a nuisance — repeated shocks strain joints, valves and appliance hoses. Here's how to track it down.
Updated October 2026 · Rooter Pros, Burbank-based mobile plumber · CSLB #917630
What you'll need
A short list:
- Hose-bib pressure gauge — to check whether pressure is too high
- Flashlight — for looking along exposed pipes
- Pipe straps or cushioned clamps — for loose pipes you can reach
- A helper — to open and close valves while you listen
Find it, then fix it.
Most water hammer comes down to fast-closing valves, high pressure, or pipes that can move.
Find which fixture triggers it
Have a helper open and quickly close each faucet, flush each toilet and run the washer and dishwasher while you listen. Note which ones cause the bang. Washers, dishwashers and ice makers are common culprits because their electric valves snap shut.
Check your water pressure
Screw a gauge onto a hose bib and read it with no other water running. High static pressure makes water hammer much worse. California's plumbing code generally calls for a pressure regulator when incoming pressure is high — if your reading looks high, have a plumber check your regulator. Ask your utility what's normal for your street.
Recharge the air chambers
Some older homes have air chambers — capped vertical pipes near fixtures — that cushion the shock. Over time they fill with water. To recharge: shut off the main valve, open the highest and lowest faucets in the house to drain the lines, wait a few minutes, then close them and turn the main back on slowly.
Secure loose pipes
Look under the house, in the garage or in the attic along runs you can reach. Pipes that rattle against framing make the noise louder and can wear through. Add straps or cushioned clamps — snug, not crushed — and keep metal pipe from rubbing on other metal.
Slow down the valve
Close faucets more gently. For a washing machine or dishwasher that bangs every cycle, the fix is usually a water hammer arrestor at the connection — a small device with an air cushion that screws on between the valve and the hose.
Not every noise is water hammer.
Match the sound to the cause before you start fixing.
Water hammer
A single loud thud or bang right when a valve closes. Fix with arrestors, pressure regulation or securing pipes.
Expansion
Light ticking or creaking as hot water runs is pipes expanding against framing. Usually harmless; cushioned clamps help.
Loose pipe or worn part
Chattering while water flows can be a loose pipe, a worn faucet washer, or a toilet fill valve. Narrow it down by fixture.
Why it matters in an earthquake zone
Pipes that are already loose and banging have less margin when the ground moves. Securing them is part of a good earthquake plumbing checklist. And if your washer bangs, check its supply hoses at the same time — braided stainless hoses are a common upgrade over old rubber ones.
When to call a pro.
Call if any of these apply:
Pressure reads high
A failing or missing pressure regulator lets street pressure hammer your fixtures. Setting or replacing one is plumber work. See plumbing repairs.
You can't reach the pipes
If the banging is inside walls or under a slab, securing pipes means opening things up — or adding arrestors at the fixtures instead.
Leaks appeared after the banging started
Repeated shocks can loosen joints. A new drip near a valve or fitting deserves attention before it becomes a bigger leak.
Rooter Pros is open 24/7 — flat-rate pricing agreed before work starts.
Call (818) 669-9019Water hammer FAQ
Straight answers, no sales pitch.
Is water hammer dangerous?
It's not an emergency, but repeated pressure shocks can loosen joints and stress valves, appliance hoses and fittings over time. It's worth fixing.
What is a water hammer arrestor?
A small device with a sealed air or gas cushion that absorbs the pressure spike when a valve closes. They're commonly installed at washing machine and dishwasher connections.
Why did my pipes start banging suddenly?
Common reasons: waterlogged air chambers, a new appliance with fast-closing valves, a pressure regulator that's failing, or a pipe strap that came loose.
Can I install an arrestor myself?
Screw-on arrestors for washing machine valves are a simple DIY install. Arrestors that need to be soldered or added inside walls are a job for a plumber.
Pipes still banging?
If this doesn't work or you'd rather not mess with it, call (818) 669-9019. 24/7 emergency service · Free estimates · Upfront flat-rate pricing