How to Use Water Hammer Arresters to Stop Banging Water Lines

Updated: Feb. 12, 2021

Stop water hammer with simple add-on arresters

water hammer arrestorFamily Handyman
Stop water hammer with easy-to-install, inexpensive arresters. Simply add them between the shut-off valve or faucet and the incoming water supply.

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Install water hammer arrestors to prevent clanking pipes

Water hammer arrestor cutaway

The sliding piston absorbs sudden pressure changes and keeps the pipes from banging.

If your plumbing bangs and clangs like a truckload of scrap metal, you’ve got “water hammer.” Water develops momentum as it flows fast through pipes. When a valve closes quickly and stops the flow, that momentum shakes and pounds pipes. A water hammer arrestor cures this condition with a cushion of air that absorbs the momentum. Before you install a water hammer arrestor, determine which faucets or valves in your house cause the noise. Washing machines and dishwashers are prime suspects because their automatic valves close fast. Arresters for washing machines have screw-on connections, making them as easy to attach as a garden hose. Other arresters connect directly to 1/2-in. pipe, often under sinks. You usually have to cut pipes and add tees to install them. Check the packaging for installation details. A water hammer arrestor costs about $10 each at home centers and hardware stores.

Required Tools for this Project

Have the necessary tools for this DIY project lined up before you start—you’ll save time and frustration.

  • Adjustable wrench
  • Pipe wrench
  • Pliers
You may also need copper soldering tools or tools for cutting and joining CPVC (plastic) pipe, depending upon your situation.

Required Materials for this Project

Avoid last-minute shopping trips by having all your materials ready ahead of time. Here’s a list.

  • Water hammer arresters