Water pipes for washing machines often bang and vibrate when the water shuts off. Quiet those pipes and prevent possible leaks by installing screw-on water hammer arresters at the water valves that serve the washing machine. Sealed water hammer arresters like the one we used here (made by Sioux Chief and sold at home centers and plumbing supply stores) are perfect for this situation. They’re designed to screw directly onto your laundry valve and accept the hose fittings from your washing machine. The arresters will operate in any position, so they’ll work even if your supply valves are installed at weird angles.
Sprinkler timers on your outside hose bibs can also cause water hammer because they shut off so quickly. If your pipes bang when the timers shut off, install a screw-on arrester in front of the timer. Make sure you remove arresters in the fall if you live in the frost belt.