Plumbing tips · October 13, 2026
Haunted pipes? Banging when a faucet shuts off
A thump or bang in the walls the moment a faucet, the washing machine or the dishwasher shuts off is not a ghost. It is water hammer, and it is worth fixing, because every bang is a jolt to the pipes and valves.
What water hammer is
Water moving through a pipe has weight behind it. When a valve snaps shut, that moving water stops all at once and slams into the closed valve, and the shock travels back down the line. The bang you hear is the pipe jumping.
Why it happens in some houses and not others
Fast-closing valves make it worse — washing machines, dishwashers and ice makers shut off with an electric valve in an instant. High water pressure makes the water hit harder. And pipes that are not strapped down well are free to move and knock against the framing.
Check the water pressure first
A pressure gauge that screws onto an outside faucet tells you what the house is running at. If it reads above 80 psi, the pressure is too high for the house and a pressure reducing valve is usually the fix. If the house already has one, it may have failed.
The fixes
A water hammer arrestor is a small device with an air cushion that fits near the valve that is causing the bang, most often at the washing machine box or under a sink. Loose pipes can be strapped. Bringing high pressure down helps everything in the house, not only the noise.
Questions we get asked
Is water hammer dangerous?
Not in the moment, but over time the shock is hard on fittings, valves, supply lines and the appliances themselves. A joint that has been banged on for years is more likely to start leaking.It only bangs when the washing machine fills. Why?
The washing machine valve shuts off very fast. An arrestor at the washing machine box is usually what that needs.What is normal water pressure for a house?
Most houses run somewhere around 40 to 60 psi. Plumbing code caps house pressure at 80 psi, and above that a pressure reducing valve is required.Plumbing questions we answer
Where we go
Parker, Wise and Tarrant County, out of the shop in Springtown. Springtown, Weatherford, Azle, Boyd, Decatur, Newark, Millsap, Fort Worth and the country in between.
Call 817-487-8866