According to PlumbingMart, water hammer can be eliminated by reducing water flow to appliances or installing AA-sized water hammer arresters on faucets and appliances. Water cushions can also be used as a temporary fix to eliminate water hammer.
If the water hammer occurs while using an appliance, locate the valve that controls the water flow to the appliance, turn the water pressure down and test the appliance to ensure it still works properly. It may be necessary to install air cushions or water hammer arresters if the appliance is not receiving the correct amount of water after adjusting the water flow. Begin by turning off the water to the home at the main water valve, then drain the water lines by turning on all faucets in the home until water stops dripping.
To install a water hammer arrester, locate the valve or faucet where the problem is occurring. Measure the pipe, and purchase a T-shaped pipe fitting and a water hammer arrester in the appropriate size, then install according to the directions on the water hammer arrester.
To install a water cushion, drain the water lines and measure the pipe, then cut the pipe and install a T- shaped fitting. On the top side of the T-shaped fitting, use plumbing glue to install an 18- to 24-inch piece of PVC pipe that has been fitted with a cap on the top end of the pipe.