What you experienced is called “water hammer.” When water flow is halted quickly, the water pressure has lots of energy that must be dissipated. If the water can bounce against an air cushion, pipes won’t pound. Most homes have anti-hammer devices installed in the water service piping. Older homes have a foot-long elbow of pipe with air trapped at the top (as shown in the following illustration “A”) located at one or several places in the system. New homes have a manufactured air chamber device (as shown in the following illustration “B”). Over time, the older type of anti-hammer device can lose the air cushion in the pipe leg and no longer be effective. To reintroduce the air cushion in your pipe system, do the following:
a) Turn off the water to the home at the main shut-off valve, which is either at the water meter or where the water service enters the house.
b) Open all faucets and allow the water to drain from them.
