Older homes generally have pipe fittings called air chambers located on each hot and cold water line at or near each faucet or water inlet valve and are rarely visible. The air chambers act as a shock absorber for water flowing at high speed. A plumbing bladder is not a sophisticated device. The cushion is often a device manufactured by a plumber.
It is made of a simple pipe attached to the water supply lines between the shut-off valve and a faucet, spigot, or any plumbing outlet. Ready-to-use plumbing air chambers are also available. It is nothing more than a piece of pipe plugged at one end, attached to a supply line at the other and containing air. Most air chambers are installed vertically on horizontal supply lines.
If the supply line is already in the vertical position, an additional length of short horizontal pipe can be added. Since this dead-end pipe is installed so that it partially intersects the water flow, the pipe also contains an air pocket. Water hammer, also called hydraulic shock, is “a concussion sound when moving water against the sides of a pipe or container,” (Illinois State Plumbing Code). Water hammer is the result of a rapid deceleration of water flow in an enclosed space, such as a pipe.
There are a few ways to solve this problem, which require simple parts and technical knowledge. A water hammer suppressor, for example, is a device used to absorb pressure increase when the flow of water suddenly stops. A device called an air chamber may be required instead of a mechanical water hammer suppressor. An air chamber is an extension of the water supply pipe near the pipe fitting that provides the air cushion to absorb hydraulic shock.
If you look at the image below, the pink lines you see are the actual “air chambers”, while the other lines are the hot and cold water supply, and the drain and vent pipes. The most common cause of a water hammer is an air chamber (or several air chambers) with too much water in it. Air chambers are vertical pipes that regulate pressure and prevent water from forming waves in the supply pipes. If you don't have them, which is unlikely unless your plumbing is very old, ask a professional to install them at key points in your system to eliminate the waves that cause water hammers.
Many homes have air chambers installed inside their walls, but sometimes the air chamber can stop working properly if it gets soaked in water.