Quick Answer:
If you hear unusual noise while the dishwasher runs, first identify when it happens—fill, wash, drain or shutoff. Many sounds come from normal parts working (pumps, valves, circulating motor) or from loose mounts and vibrating water lines. If the noise comes from hidden pipes or an integrated device (water softener, pump), a plumber can safely isolate and diagnose the source.
Why This Happens
- Fill phase: valves open and water enters under pressure. A noisy solenoid or a partial restriction can make high-pitched or chattering sounds.
- Wash/circulation: the motor and pump move water. Worn bearings or loose brackets make humming, grinding or rattling noises.
- Drain: the drain pump and the garbage disposal connection can rattle or clatter, especially if a clamp or hose is loose.
- Shutoff: sudden valve closure can cause a bang or knock known as water hammer in the piping.
- Vibration transfer: supply lines, cabinets and countertop panels can amplify normal appliance sounds if fittings are loose or lines touch framing.
- Integrated systems: built-in softeners, booster pumps, or remote motors in the house plumbing can tick, hum or bang when the dishwasher triggers them.
Step-by-Step What to Do
1. Run the cycle that makes the noise
Start the exact dishwasher program that triggers the sound. You need to recreate the problem to identify when it occurs.
2. Listen for the exact phase
Pay attention to whether the noise happens during fill, wash/circulate, drain or at shutoff. Note the moment precisely—this points to valves, pump, or piping.
3. Feel nearby supply and drain lines
Carefully touch visible supply lines and hoses (don’t touch electrical parts). You may feel vibration or a thump that matches the sound. That helps tell if the appliance itself or the plumbing is vibrating.
4. Watch and compare with other appliances
Run comparable cycles on other appliances (washer, ice maker, or another dishwasher if present) to see if similar noises occur. This helps determine whether the issue is the dishwasher or the home plumbing. If you notice a similar knocking when other appliances stop, the problem may be in the pipes.
5. Inspect visible fittings and mounting
- Check clamps, hose connections and the dishwasher mounting brackets for looseness or contact with the cabinet.
- Listen while you gently press panels or hoses to see if contact changes the noise.
6. Note any related house devices
If the sound seems tied to other systems—like a water softener regenerating, a booster pump starting, or house-level valves—record when those run. If the timing matches, the hidden device may be the cause. For related problems, homeowners sometimes look up similar issues like **Rattling during dishwasher drain** or **Hammer when ice maker shuts off** for comparison.
What Not to Do
- Don’t disassemble appliances or remove safety covers to chase sounds. Internal motors and electronics can be dangerous.
- Don’t bypass safety devices (float switches, pressure reliefs or door interlocks) to test or silence a noise.
- If the noise is tied to built-in systems like softeners or pumps, have a plumber diagnose it properly rather than trying to reroute or disable those systems yourself.
When to Call a Professional
- Persistent banging or loud knocks that match a valve closing—possible water hammer or loose pipe anchor.
- Noise that seems to come from inaccessible piping or a house-level pump or softener—these require isolation and safe testing.
- Unusual grinding or burning smells from the appliance, or if the appliance shows error codes while noisy.
- Any visible leaks, sudden loss of water pressure, or electrical concerns—stop using the appliance and call a pro.
A plumber can isolate sections of piping and test integrated systems safely, and will have the tools to secure or add arrestors for water hammer and to replace worn valves or mounts.
Safety Notes
- Always unplug the dishwasher or switch off its breaker before touching internal parts or making repairs.
- Turn off the water supply before loosening any water fittings.
- Do not stick your hands near moving parts while the appliance is running.
- When in doubt about electrical, gas or hidden plumbing work, contact a licensed professional.
Common Homeowner Questions
- Q: Could the noise mean the dishwasher is failing? A: Not always—many noises are from loose parts or piping; persistent grinding or burning should be checked.
- Q: Is water hammer dangerous? A: It can stress joints and fittings; if you hear repeated loud bangs, get a plumber to add an arrestor or secure pipes.
- Q: Can I run the dishwasher until a plumber arrives? A: If the noise is minor, yes, but stop use if you smell burning, see leaks, or hear persistent loud knocks.
For more related articles, see the Noises Only When Appliances Run hub.