"Water hammer" is a plumbing phenomenon that many people are familiar with even if they haven’t heard the name. It is a loud, recurrent banging or knocking that comes from household pipes. If not addressed, it can lead to pipe damage. Below are answers to a few common questions about water hammer.

What You Should Know About Water Hammer

What causes it?

Water hammer, also known as hydraulic shock, occurs when water flowing rapidly through your pipes stops or changes direction suddenly. The abrupt change creates a shock wave that causes the pipes to shake. The sound occurs when the shuddering pipes rattle against each other or against wooden supports.

When does it occur?

PlumbingWater hammer typically occurs when you abruptly shut off access to a water pipe using a quick-close valve. The greater the water volume and speed prior to being shut off, the more likely the pipes are to experience hydraulic shock. Therefore, you may hear it after a washing machine fill cycle shuts off or you turn off the shower. It can occur in both hot- and cold-water pipes.

How can it harm your plumbing system?

The rattling can damage expansion joints and gaskets and result in leaks and ruptured pipes. Water hammer can even damage pumps and plumbing measurement instruments. Furthermore, leaks and pipe ruptures can lead to additional property damage and expensive, troublesome mold growth.

How can you address the problem?

You can often fix the problem by changing the type of valves used in your system. Quick-closing piston or swing valves result in the water slamming to a stop. Silent or spring-assisted check valves close slowly to prevent the sudden shock. Securing loose pipes—or wrapping them in pipe insulators to prevent contact—will also help reduce noise.


If you are experiencing water hammer, contact Valley Mechanical in Naples, NY, for professional assistance with your plumbing system. They have served Ontario County since 1999, specializing in sewer snaking, furnace repair and maintenance, water conditioner installation, and well pump repair and replacement. Visit their website to learn more or call (585) 374-6866 to schedule an appointment.