How to Fix Water Hammer in Your Pipes

Water hammer sounds like a frantic plumber is pounding on your walls with a mallet, but it is actually a sign of physics fighting against your home's plumbing. That sharp, jarring bang occurs when water moving through your pipes suddenly hits a closed valve, sending a shockwave backward through the system. It is more than just a nuisance; that constant pressure fluctuation can eventually loosen joints and compromise your fittings. Fixing it is usually a matter of restoring the air cushions designed to absorb those surges. While older homes rely on vertical capped pipes to act as shock absorbers, these often become waterlogged over time. Modern solutions are more reliable and easier to install. When done well, your pipes will run silently and the life of your plumbing system will be extended by years.

  1. Shut Off and Open All Taps. Locate your main water shut-off valve and turn it clockwise until it stops. Once the main line is closed, open every faucet in the house to drain the remaining water out of the pipes.
  2. Drain Every Line Completely. With all faucets open, allow the water to drain until the system is entirely empty. Air must be allowed to enter the pipes to replace the water you are draining out.
  3. Refill With Air Pockets. Once the system is dry, turn the main water supply back on slowly. As the water begins to flow, the empty pipes will refill with air first, creating the natural cushion needed to absorb future shock.
  4. Test for Remaining Bangs. Go to the faucet or valve where you originally heard the loudest banging. If the noise continues, the integrated air chambers may be permanently waterlogged and need mechanical assistance.
  5. Mount the Arrestor Device. For persistent issues, install a water hammer arrestor directly onto the supply line. Unscrew the supply hose from the fixture, attach the T-fitting, screw the arrestor into the T, and reconnect the hose.
  6. Strap Down Vibrating Pipes. Inspect the pipes near the noise source for movement. Use pipe straps or cushioned clamps to secure any vibrating copper or PEX lines to the wall studs.