Water hammer is the loud bang or thud you hear in pipes when flowing water is stopped suddenly, such as when a valve snaps shut. Over time, those repeated shocks can loosen fittings, damage valves, and weaken pipes.
What Causes Water Hammer
Water moving through a pipe has momentum. When a valve closes quickly, the water slams to a stop and sends a pressure wave back through the pipe. That wave causes the banging sound. Appliances with fast-closing valves, like washing machines and dishwashers, are common triggers. Single-handle faucets that are snapped shut can cause it too. Toilets with fast fill valves may also make a quick knock when the tank finishes filling.
Signs to Watch For
- Loud banging or knocking after a faucet or appliance shuts off
- Pipes that shake or rattle in the walls
- Noise that happens at the same time as a washer or dishwasher cycle
- New drips at fittings near the noisy pipes
Can It Damage Pipes?
Yes, over time. Each pressure spike puts stress on joints, valves, and appliance hoses. Loose pipes can bang against framing, which can wear holes or loosen straps. High household water pressure makes water hammer worse, since the water carries more force when it stops.
How It Can Be Fixed
The fix depends on the cause. Options include securing loose pipes with proper straps, adding water hammer arrestors near fast-closing valves, and lowering high water pressure with a pressure-reducing valve. Older homes may have air chambers that stopped working and need attention.
A plumber can test your water pressure and listen for where the noise comes from. Closing faucets gently is a free habit that helps in the meantime.
If banging pipes have already led to a split or leaking line, repairing the damaged pipe should come first. For noisy plumbing that has not yet leaked, you can have the noise traced by a plumber by calling (833) 603-1840.