Noises in Pipes When Closing the Tap: The Water Hammer
Do your pipes sound like a hammer strike when you shut off a tap quickly? This can burst your plumbing. We explain what it is and how to fix it.
Reviewed by Carlos Martínez — Certified Technician
Approved by supervisor Rafael Casas de las Peñas Del Corral
You're washing your hands, you quickly close the mixer tap, and suddenly you hear a loud *CLONK!* inside the wall. It sounds like someone hit the pipe with a hammer.
This common and startling plumbing phenomenon is known as "Water Hammer".
### Why does water hammer occur? Water travels through your pipes at high speed and under pressure. When you shut off a tap suddenly (or when the washing machine abruptly cuts the water intake), all that moving mass of water violently crashes against the closed valve.
The energy of the impact creates a shockwave that travels backward through the pipe, making it vibrate and bang against the wall or its brackets.
### Is it dangerous for my house? Yes, very. It's not just an annoying noise. That brutal impact progressively weakens the joints and solders of copper or multilayer pipes. Over time, water hammer can cause a joint to fail, creating a hidden water leak inside the wall.
### How to fix it 1. Close taps slowly: Especially single-lever mixer taps. Pushing the lever down gently allows the water to slow down gradually. 2. Check overall pressure: Sometimes the issue is that water enters the house with too much pressure. A plumber can install a pressure reducing valve at the main water inlet. 3. Install arrestors: There are small devices (water hammer arrestors) that are installed near washing machine or dishwasher valves. They contain an air chamber that absorbs the impact of the water.
Are your pipes banging loudly and you fear they might burst? Contact PowerPro Madrid. Call us or send a WhatsApp; our expert plumbers will evaluate your pressure and protect your installation.
