Symptoms
- Loud bang or thud in the walls when the dishwasher starts filling
- Noise happens at the same point in every cycle
- Other appliances (like the washing machine) cause similar noise
- Pipes visibly vibrate or shake
Likely causes
- CommonWater hammer from high water pressure or missing air chambersFast-closing valves stop water abruptly, sending a shockwave through rigid pipes without cushioning.
- PossibleLoose or unsecured pipesPipes that aren't well strapped down amplify the banging sound.
- PossibleFailing or worn water inlet valveA valve that snaps shut harder than normal can worsen hammer noise.
- PossibleHigh household water pressurePressure well above normal residential levels makes hammer more likely and more forceful.
What to do
- Check if the same banging happens with other appliances like the washing machine or when faucets shut off quickly, which points to household water hammer rather than the dishwasher.
- Check your home's water pressure with a simple gauge from a hardware store; pressure over about 80 psi increases hammer risk.
- Look for exposed pipes and check that they're properly strapped or secured, especially near the dishwasher connection.
- Consider installing a water hammer arrestor near the dishwasher's supply line if the noise is consistent.
- If pressure is unusually high, a plumber can install a pressure-reducing valve for the whole house.
- If the noise seems isolated only to the dishwasher and worse than other appliances, have a technician check the inlet valve.
Tools and parts
- Water pressure gauge (optional)
Water hammer arrestorSearch: “dishwasher water hammer arrestor”
When to call a pro
If the issue is house-wide water hammer, a licensed plumber can install arrestors or a pressure-reducing valve; if isolated to the dishwasher's valve, an appliance technician can help.
Safety
Generally low risk
Generally low risk for a careful person. Stop if anything looks different from what this guide describes.