To stop water pipes banging, match the remedy to the cause: water hammer may require pressure testing or a suitable arrestor, moving pipes may need securing, and hot-water pipes may need clearance for thermal expansion. You can identify the trigger and check exposed pipes safely, but a licensed plumber should alter pipework or pressure-control devices.
Identify the likely cause
- One sharp bang when a tap, washing machine or dishwasher stops: likely water hammer, a pressure surge caused by flow stopping suddenly.
- Rattling or repeated knocking while water flows: likely pipe movement caused by inadequate support or contact with framing.
- Ticks or dull knocks as hot pipes warm or cool: likely thermal expansion, with the pipe binding against a support, penetration or building material.
- Noise at several fixtures: may indicate a broader pressure or pressure-control issue requiring testing.
If the sound comes from the water heater rather than the connected pipes, it may have a different cause and should be assessed separately.
Make these safe checks
- Operate one fixture at a time and note whether the noise happens when water starts, runs or stops.
- From floor level, watch accessible, exposed pipes for movement. Do not enter roof or underfloor spaces, remove wall linings, reach near electrical equipment or touch hot pipes.
- If one appliance consistently causes a forceful bang, stop using it where practical until the cause is assessed. Do not repeatedly trigger a severe bang.
- Look for fresh water or dampness without touching the pipe. If there is a leak, stop using the affected fixture. Turn off the property’s water supply only if the isolation valve is accessible and safe to operate.
What a plumber may need to do
Depending on the diagnosis, a plumber may:
- secure or cushion moving pipes and correct points where they rub or bind
- test the water pressure and assess pressure-control components
- fit a correctly selected water hammer arrestor near the valve causing the surge
- repair or replace a faulty pressure-control device
- adjust pipe support or clearance to allow thermal movement.
Hot pipes can burn, while loosening or cutting pressurised or concealed pipework can cause flooding or injury. Do not install arrestors, pressure-reducing valves or concealed supports yourself.
Arrange an assessment if the banging is severe, persistent, becoming more frequent, affects several fixtures, comes from concealed or hot-water pipework, or occurs with leaks, pressure changes or forceful pipe movement. Contact our licensed Sydney water-pressure plumbers to test the system and identify the appropriate repair.