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Stop Banging Water Pipes

The best cure for banging water pipes is a water hammer arrester with a lubricated internal piston. The sealed piston works better than capped pipes, which eventually fill with water.

By the DIY experts of The Family Handyman Magazine

Adding a water hammer arrester

Water hammering is caused by the quick shutoff of water supply lines. The energy in flowing water has to go somewhere, and when a valve is shut off, the pipes can flex and “hammer” against anything close—like nearby studs, joists or other water pipes. Solenoid-triggered valves, like the ones in dishwashers, washing machines and water softeners, shut off almost instantly, not only causing the most ferocious hammering but also putting strain on rubber hoses and copper sweat fittings. Hand-controlled faucets usually don’t cause as much hammering because the shutoff is more gradual.

The traditional solution of adding a capped length of copper pipe (A) works by trapping a bubble of air that acts as a shock absorber for the back pressure, but it only works for a while. Eventually the air bubble shrinks because the air gets absorbed by the water until it disappears completely. Instead, install a manufactured water-hammer arrester (B and C), which is available at home centers. It isolates the pocket of air from the water in the pipes with a rubber-gasketed piston. The closer you locate the arrester to solenoid valves, the better. The model shown is designed to mount between the spigot and washing machine feed lines. If necessary, add more in-line arresters in other water pipes near faucets or valves to further reduce hammering.

A. Vertical, capped

A. Vertical, capped

B. In-line

B. In-line

C. Screw-in style

C. Screw-in style

Types of Water Hammer Arresters

The three most common types of water hammer arresters are:

A. Vertical, capped
B. In-line
C. Screw-in style

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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
    • Plumbers tape
    • Soldering torch
    • Tube cutter

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 arrester
    • Flux
    • Solder

Comments from DIY Community Members

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December 31, 7:14 PM [GMT -5]

is this the same water hammer arrester uses on the picture the same that use on the washer itself. How can it install to the washer itself ?

December 31, 7:08 PM [GMT -5]

if the water hammer noise comes inside from the side of the dry wall & shaking it (not the back of the washer), will the water hoses attached to the washer hoses helps ?

January 22, 10:24 AM [GMT -5]

The picture in this article shows the hammer arrestors right off the washing machine box.. which works for normal top load washers..... It should have
noted that if you have the front load high efficency models with the fast closing
valves.. having it setup like that won't work.. you need to install the hammer
arrestors right off of the washer itself.. you'll find that the hammer then goes
away. Just that 3 feet of hose is enough to hammer..
I eventually installed the hammer arrestors on all my sinks, toilets as well
because if you slam the sink valve shut you'll get a hammer also

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Stop Banging Water Pipes

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