Why Do My Pipes Bang? Causes and Simple Fixes

That Banging in Your Walls Isn’t the House Settling

You turn off the kitchen tap and something thumps inside the wall. The washing machine starts filling and the whole house seems to knock twice.

It’s not the house settling. Water moving through a pipe is heavier and faster than it feels at the tap, and when a valve shuts in an instant, all that water stops dead. The force has to go somewhere, so it goes into your pipes, and you hear it.

• One sharp bang A single thump the moment a tap or valve closes.
• A rattle in the wall The noise runs along the pipe instead of stopping.
• The tap shudders You feel it in your hand as you close it.
• The washing machine sets it off Same noise, same point in the cycle, every time.

Plumbers call this water hammer. Most of the time it’s a nuisance rather than an emergency, but it’s worth sorting, because every bang is a small knock against your pipe joints. We get called out for it right across Lugarno, usually in homes where the pipes have been in the wall for decades and a new appliance has just joined the mix.

A tap you turn by hand closes gradually, so the water slows down as you go. A valve inside an appliance doesn’t. It snaps shut in a fraction of a second, and that’s when you get the bang. Whether you hear it depends on your pipes. Pipework that’s properly clipped in place absorbs the knock quietly. Pipe sitting loose in a wall cavity has room to move, so it hits the timber and the noise carries through the house.

• Appliance valves Washing machines and dishwashers shut off instantly, with no slowdown.
• Loose pipework Pipe that isn’t clipped down knocks against framing every time.
• High water pressure Strong pressure makes every sudden stop harder.
• Worn tapware Old washers and cartridges can make a tap snap shut instead of closing smoothly.
• Long pipe runs The further the water travels, the more weight there is to stop.

The most useful thing you can work out is which fixture starts it. If it’s only the washing machine, that’s one job. If every tap in the house sets it off, the cause is usually pressure or the way the pipes are held in place.

How we track down banging pipes

We start by finding which fixture triggers the noise and following where it travels. That tells us whether we’re dealing with one appliance, loose pipe or pressure across the whole house, before anything gets opened up.

One knock from one tap is a different job to banging that happens every time a valve closes anywhere in the house. Clipping down one length of pipe won’t help if the real problem is pressure coming into the property.