Symptoms
- Loud bang or thud right as the faucet is closed
- Noise seems to come from inside the wall
- Happens with quick-closing faucets or appliances more than slow ones
- Noise is occasional or has gotten more frequent
Likely causes
- CommonMissing or failed water hammer arrestorThese small air-cushioned devices absorb the shock of sudden shutoff; older ones lose their air cushion over time.
- CommonLoose pipes banging against framingUnsecured pipes can slam against studs or joists when pressure surges.
- PossibleHigh household water pressureExcess pressure makes any shockwave more forceful.
- PossibleAir chambers waterloggedOlder homes used vertical air-filled pipe sections that can fill with water over time and stop working.
What to do
- Note which fixture triggers the bang most consistently to help narrow down the location.
- Check if the home has visible air chambers or arrestors near that fixture's shutoff valves.
- If pipes are accessible, look for any that appear loose or unsecured near where the noise seems to originate.
- Secure any loose pipe with a proper pipe strap or clamp rather than tape or wire.
- Consider having a water hammer arrestor installed at the fixture if one isn't present, following manufacturer instructions or a plumber's install.
- If pressure feels unusually high throughout the house, a pressure gauge on an outdoor spigot can confirm; normal residential pressure is roughly 40–60 psi.
- If pressure is high, a plumber can install or adjust a pressure-reducing valve for the whole house.
Tools and parts
- Pipe strap
- Pressure gauge (optional)
Water hammer arrestorSearch: “water hammer arrestor faucet”
When to call a pro
Call a plumber if the banging is loud, frequent, or you can't access the pipes to secure or install an arrestor yourself.
Safety
Generally low risk
Generally low risk for a careful person. Stop if anything looks different from what this guide describes.