Fixing Water Hammer

Scott Cam showed how to stop ‘water hammer’, or pipes that bang, clang and vibrate when you turn off your taps. As well as being extremely noisy, water hammer can cause water heaters, joints, seals and connections to fail, and taps to leak.

What causes it?

Water hammer is a shock wave of high water pressure in the pipes, caused by the sudden closing of a valve. The water does not compress, but crashes into the closed valve again and again, creating a loud hammering noise. The wave eventually dissipates within the piping system. There are several common causes of water hammer, including:

  • poor pipe installation
  • ‘flick mixer’ taps
  • faulty tap washers
  • solenoid valves on appliances such as dishwashers and washing machines
  • high water pressure

What to do

  • All pipe work should be securely fastened during construction. It can be difficult to do this after construction, so the use of water hammer suppression devices may be necessary.
  • Instead of ‘flick mixer’ taps that shut the water off suddenly, choose ‘soft close’ mixer taps with a built-in shock absorber system.
  • If vibrating pipes occur in a particular area, for example the kitchen, it may help to replace plastic or ceramic tap washers with brass tap washers. Ceramic washers can break easily, and when that happens you may have to shut off the water at the mains and call a plumber to repair the tap.
  • Install taps with washers that you can easily replace yourself, rather than having to call a plumber.
  • Install water hammer arresters on washing machine taps. Often the solenoid valve in washing machines causes the pipes to rattle and clunk.
  • Reducing your water pressure can reduce water hammer. Call a plumber and have a ‘pressure limiting valve’ or water hammer arrester installed.
  • Check with local water authorities for regulations in your state.

Further information

  • Hammer arresters cost approx. $50 – $60 at hardware stores
  • Soft close single lever mixer taps cost from $60 from hardware or plumber suppliers stores