Water hammer is potentially dangerous and could hurt your plumbing system. Referred to in technical circles as hydraulic shock, water hammer is the result of water stopping or changing direction very quickly. When this happens, a shock wave goes through your pipes, forcing your pipes to move, shake, and bang together.

Can knocking pipes cause damage?

A: The banging racket you're hearing is called “water hammer,” a form of hydraulic shock that occurs when the shut-off valve on a high-pressure water line suddenly closes. ... More than just produce an annoying clamor, water hammer can actually damage the pipe connections and joints, resulting in leaks and costly repairs.

Should I worry about banging pipes?

When the copper expands as hot water passes through it, it can bang into joints, brackets, other supports and even the walls of your home. Expanding copper and the noise that come with it is nothing to worry about – it is a well-known property of the metal.