Common causes of water hammer include improper installation of plumbing and air chambers that become waterlogged. The condition occurs when a user turns off a tap quickly, causing a rapid halt of the moving water. The process creates shock waves moving through the pipes causing the hammering noise.
Fixing water hammer due to improper plumbing requires installing air chambers in the correct location. These chambers provide a cushion of air that absorbs the vibrations without rattling the pipes.
If the water system does not normally hammer but suddenly starts, the issue is usually the failure of the air chambers. Because the water in the plumbing system is under pressure, it absorbs the air and fills the chamber. Because water does not compress like air, the system starts to hammer.
Fix the problem by turning off the water supply valve for the home and opening the tap to drain the water. If the air chamber is below the hammering faucet, open the lowest outside faucet to drain the water, then close the taps, and turn on the main valve. As water fills the pipes, it compresses air back into the chamber.
If the system continues to hammer, the chamber may contain mineral deposits. Turn the water back off, open the lid to the chamber, and clean the minerals from inside it.