You’re hearing loud banging or knocking in your pipes when you turn taps off — that’s stressful, but it’s usually fixable.
Loud bang when you turn off a tap quickly (kitchen or bathroom)
Is this your problem?
What to do
• Turn the tap off slowly for now to reduce shock.
• Check if it’s worse on the cold side — that’s common in UK homes.
• If it’s only one tap, the washer or cartridge may be worn. Replace it if you’re confident.
• If the noise stops when you slow the tap, pressure shock is the cause.
Safe DIY: replacing a tap washer or cartridge.
Stop and call a plumber if the bang is violent or shakes the pipework.
Banging when washing machine or dishwasher stops filling
Is this your problem?
What to do
• These appliances shut valves instantly — a classic water hammer trigger.
• Fit a washing-machine water hammer arrestor on the cold feed.
• Make sure the appliance tap is fully open, not half-turned.
Safe DIY: fitting a screw-on arrestor to the appliance hose.
Call a plumber if pipes jump or thud inside walls.
Pipes knocking inside walls or under floors
Is this your problem?
What to do
• Pipes may be loose or not clipped properly.
• If accessible, add pipe clips or foam lagging to stop movement.
• In older UK houses, copper pipes often expand and hit timber.
Safe DIY: securing visible pipes.
Stop if pipes are hidden — don’t open walls yourself.
Banging started after boiler or plumbing work
Is this your problem?
What to do
• Air may be trapped in the system.
• Turn off the mains, open all taps (hot and cold), then close them slowly.
• Turn mains back on gently.
Safe DIY: controlled draining and refilling.
Call a plumber if noise remains — pressure may need regulating.
Happens across multiple taps, hot and cold
Is this your problem?
Check cold water pressure problem also.
What to do
• Your mains pressure may be too high (common in newer UK builds).
• Check if you have a pressure reducing valve (PRV).
• If not, one may be required to protect pipes and appliances.
Not DIY.
This needs a qualified plumber.
Is it safe to fix this yourself in the UK?
| Safe DIY | Do NOT DIY | Stop Immediately If | Call a Plumber When |
|---|---|---|---|
| Replacing tap washers or cartridges | Cutting into walls or floors | Pipes visibly jump or shake | Noise is system-wide |
| Fitting appliance arrestors | Altering mains pressure | You hear cracking sounds | It follows recent plumbing work |
| Securing exposed pipes | Working near boilers or sealed systems | You see leaks or dripping | You suspect high mains pressure |