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How to Identify and Prevent Water Hammer

Water hammer can be more than just a nuisance. If not corrected, the shock wave cause by water hammer may burst your pipes. But there are ways to reduce or even eliminate the threat.


  • TIP: Water hammer arresters are available at most hardware and home improvement stores.
  • TIP: [Switch to low-flow fixtures] Switch to low-flow fixtures if the hammer is occurring at a sink, toilet, or bathtub faucet. Low-flow fixtures can reduce -- and often eliminate -- annoying water hammer while reducing your home water consumption significantly. Get rid of the hammer and finally enjoy some peace and quiet.
  • FACT: Since 1994, all showerheads manufactured in the United States have a maximum flow rate of 2.5 gallons per minute.
  • Step 1: Determine which valve is causing the hammer, and install a water hammer arrester at the valve. Arresters contain an air bladder that absorbs the shock wave that occurs when water traveling at a high velocity suddenly stops.
  • TIP: Since you will have to cut and sweat pipes, you may want to leave this to a professional.
  • Step 2: Check the pressure in your plumbing by connecting a water pressure gauge to a faucet. Turn off everything else in your house that uses water, and then open the faucet with the gauge attached and check the reading. Anything over 60 PSI, or pounds per square inch, is more water pressure than you need.
  • Step 3: Install a pressure regulator if your water pressure is too high. Locate the pipe coming from your water meter that supplies clean water to your home, use a wrench to unscrew the union on the pipe, and screw on the regulator. Then replace the pipe and tighten the draw nut on the regulator to prevent leaks. Adjust the pressure to between 40 and 50 PSI to eliminate the water hammer.
  • Step 4: Replace the supply pipes leading to the offending valve with pipes that have a wider diameter to slow the water flow and relieve pressure.
  • Step 5: Listen for a banging sound when you close a water faucet, when your dishwasher, washing machine, or refrigerator ice maker stops, or when your sprinkler system shuts off. Water is incompressible, so when a high-pressure stream of water is suddenly stopped by the closing of a valve, an energy explosion in the form of a shock wave occurs in your plumbing.

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