Water hammer sometimes occurs when a faucet is suddenly closed. When the flow of water is suddenly stopped, its kinetic energy is expended against the walls of the piping. This causes the piping to vibrate, and leaks or other damage may result.
Water hammer may be prevented or its severity reduced by installing an air chamber just ahead of the faucet. The air chamber may be a piece of air-filled pipe or tubing, about 2 feet long, extending vertically from the pipe. It must be airtight. Commercial devices designed to prevent water hammer are also available.
An air chamber requires occasional replenishing of the air to prevent it from becoming water-logged—that is, full of water instead of air.
A properly operating hydropneumatic tank, such as the type used in individual water systems, serves as an air chamber, preventing or reducing water hammer.
In cold weather, water may freeze in underground pipes laid above the frostline or in pipes in unheated buildings, in open crawl spaces under buildings, or in outside walls.
When water freezes it expands. Unless a pipe can also expand, it may rupture when the water freezes. Iron pipe and steel pipe do not expand appreciably. Copper pipe will stretch some, but does not resume its original dimensions when thawed out; repeated freezings will cause it to fail eventually. Flexible plastic tubing can stand repeated freezes, but it is good practice to prevent it from freezing.
Pipes may be insulated to prevent freezing, but this is not a completely dependable method. Insulation does not stop the loss of heat from the pipe—merely slows it down—and the water may freeze if it stands in the pipe long enough at below-freezing temperature. Also, if the insulation becomes wet, it may lose its effectiveness.