If you have ever turned off a faucet or appliance and heard a sudden bang or thud in your walls, you have likely experienced water hammer. Although the sound can be surprising, water hammer is a common plumbing issue found in many homes.
Water hammer occurs when flowing water inside your home’s plumbing is forced to stop or change direction suddenly. When a valve inside a faucet, washing machine, dishwasher, or irrigation system closes quickly, the water inside the pipe continues moving for a moment and creates pressure waves. These waves can cause pipes to shake or knock against framing, resulting in the banging sound residents often notice.
Several everyday situations can trigger water hammer. Appliances with quick-closing valves are the most frequent cause, especially washing machines and refrigerator ice makers. High water pressure inside the home can make the problem more noticeable, and unsecured pipes behind walls may shift over time, increasing the sound.
While the noise can be alarming, water hammer is generally a plumbing issue within the home. Simple measures can often reduce or eliminate it. Residents can check to see whether visible pipes are properly secured with clamps or straps and consider having a plumber install or replace water hammer arrestors, which are small devices that absorb pressure changes inside the pipes. If indoor water pressure is unusually high, a licensed plumber can evaluate whether a pressure-reducing valve would help.
If your home suddenly begins experiencing severe banging noises, or if the sounds are accompanied by vibration, leaks, or noticeable changes in pressure, these may be signs that a plumber should take a closer look. Addressing the issue early can help prevent wear on pipes and reduce the likelihood of future problems, including expensive leaks and repairs.