We just bought a townhome and every time we use the LG Front loading washing machine there is a loud bang throughout the pipe system. I checked the back and there are already 2 water hammer arrestors (Size AA) installed on the inlet to the washing machine's hot and colt water intakes. When I checked the water pressure of the cold water it was at 80psi. Does the banging have something to do with the water pressure or could I need bigger Water Hammer Arrestors? We are on a municipal water supply.

  • How long is the pipe to the washer faucets? Does it happen with cold or hot equally? What kind of hose connection is there from the washer to the plumbing?
    – wallyk
    Aug 23, 2013 at 22:44
  • It looks like around 6ft of a braided cable between the utility sink where the cable connects in, to the intake for the washer. This happens with both hot and cold water.
    – Larry L
    Aug 24, 2013 at 0:33
  • 6
    The water hammer is caused by the fast acting valves in the washer. Water hammer arrestors don't always stop the noise, so you'll likely have to try and locate any and all points in the plumbing that are banging. Once you've found where the pipe is banging, you'll have to support and/or isolate the pipe to prevent it moving. Then you'll have to locate and support/isolate the next area, and repeat until the bang is silenced.
    – Tester101
    Aug 24, 2013 at 1:53

3 Answers 3


You may need to replace the arrestors.. they do fail eventually. Also even with them in place there may be poorly secured pipes that bang around. Try to find them and secure them properly.


You could try swapping the inlet hoses for longer ones. The theory would be that the longer rubber hoses might absorb some of the shock (by expanding slightly) as the valves close. If possible grab some 6 foot ones or similar and curl them around behind the machine.


Temporarily reduce the inlet pressure slightly by turning down the main inlet facet and see if the hammer goes away.

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