Stop water hammer with easy-to-install, inexpensive arresters. Simply add them between the shut-off valve or faucet and the incoming water supply.
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. Water hammer arresters cure this condition with a cushion of air that absorbs the momentum. Before you install arresters, 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. Arresters cost about $10 each at home centers and hardware stores.
Have the necessary tools for this DIY project lined up before you start—you’ll save time and frustration.
You may also need copper soldering tools or tools for cutting and joining CPVC (plastic) pipe, depending upon your situation.
Avoid last-minute shopping trips by having all your materials ready ahead of time. Here's a list.