Why do my pipes make a banging noise (water hammer)?
Banging pipes, known as water hammer, is usually caused by a sudden stop in water flow creating a pressure shockwave — often fixed with an air-filled arrestor.
What Causes Water Hammer?
Water hammer happens when a valve or tap closes suddenly (like a washing machine solenoid valve), causing the moving water to stop abruptly and send a shockwave through the pipework — heard as a loud bang or knock.
Common Causes
- Worn tap washers or valve seats
- Loose pipework that vibrates against joists or walls
- Missing or waterlogged air chambers/arrestors
- High mains pressure with no regulation
The Fix
A plumber can install a water hammer arrestor (a small air cushion device), secure loose pipework with clips, or fit a pressure reducing valve if mains pressure is too high. Left unresolved, water hammer can loosen joints and cause leaks over time. Call RARE on 020 7458 4949 for a diagnosis.
Reviewed by RARE Plumbing London Engineering Team — Gas Safe registered engineers serving prime London since 2013.
Related Service
Plumbing Repairs
Expert engineers across prime London