Asked on May 5, 2013

hot water pipes rattle when hot water is turned off

Lee GovanH.O. ElectricWoodbridge Environmental


We just moved into our townhouse (not new; built in '97) and have discovered that the hot water pipes bang briefly when the hot water is turned off. This doesn't happen when the cold water is turned off. Our house is two story and my husband says it seems that the noise is originating in the guest bathroom upstairs. Would appreciate any feedback
3 answers
  • What your experiencing is called water hammer. The water flows through the pipes and when a faucet or the dishwasher or washing machine turns off the flow quickly the waters motion in the pipes shakes the pipes causing the noise your hearing. Ideally the fix is to find the loose pipe within the wall that is making the offending noise and resecure it where the strap or clamp that holds it in place has failed. However this is not always easy to figure out and even if you could access to that requires in most cases opening up a wall. You do however not want to simply get used to this noise as over time this vibration noise will worsen and can even damage the pipe and cause a leak. The first thing you need to check is the water pressure to your home. If it has been increased for whatever reason it should be lowered. This alone may stop the noise. If the pressure has not be changed then you need to either support the pipe better or install water hammer arrestors on the pipes. The latter is often done at the washer and is connected to the water lines leading to the machine. This is assuming that this is the location of where the offending on and off cycle is causing the noise. If not you will need to access the plumbing nearest the offending faucet that when turned off is causing this issue and install the device near that area. Here is a link to many types and styles made to stop this issue.

  • H.O. Electric
    on May 7, 2013

    Try supporting the pipes under sink better. Use straps to do this.

    q hot water pipes rattle when hot water is turned off, home maintenance repairs, plumbing
  • Lee Govan
    on Apr 7, 2015

    The water hammer problem is easily fixed by either a plumber or a builder. Where your hot water pipes go through the joists need to be filled with builders foam to cushion the movement in the pipes when you turn your hot water off, no more noise.

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