Quick Answer:
A rattling sound when the dishwasher runs usually means a pipe or its mounting is vibrating. Often it’s caused by pressure changes, a loose strap, or a pipe knocking against framing or a cabinet. Try a few simple checks: run the water or appliance slowly then fully to see when the vibration starts, listen from an adjacent room to localize the run, and press lightly on the nearby wall or cabinet to feel movement. If you can’t access the pipe or the run is behind finished surfaces, a plumber can locate the run and secure it safely without damaging the wall.
Why This Happens
Common causes:
- Pressure pulses from valves opening and closing (sometimes called water hammer) or rapid flow changes when pumps or valves in the dishwasher cycle.
- Loose pipe straps or hangers that allow the pipe to move and hit framing, a cabinet, or a drywall surface.
- Pipes routed close to finished surfaces or wiring so vibration is transmitted and becomes noticeable.
- Air in the lines or partial blockages changing the flow pattern.
If the sound only happens with heated cycles, check Rattling only on hot water. If you notice similar noise when other appliances run, compare with Rattling when washing machine fills.
Step-by-Step What to Do
1. Reproduce the noise and watch when it starts
Start the dishwasher or open the nearby shutoff valve slowly, then open it fully. Run the cycle or let water flow so you can observe whether the vibration begins at a slow flow, or only at full flow or during a specific part of the cycle.
2. Listen from different locations
Move to an adjacent room or hallway and listen. This helps you localize which wall, cabinet, or floor run the noise is coming from. Listening from multiple positions narrows down the area to inspect.
3. Feel for movement
Press lightly on the nearby wall, cabinet, or baseboard while the dishwasher runs. If you can feel the vibration through the surface, the pipe is contacting that framing or finish and is likely loose or poorly supported.
4. Inspect visible pipes and supports
Look under the sink or in access panels for loose straps, clamps, or points where pipe touches wood or metal. Tighten accessible mounting straps or add a clamp if you feel comfortable doing so and water is off. Keep any adjustments gentle—don’t overtighten fittings.
5. When access is limited
If the noisy run is inside a finished wall, ceiling, or behind cabinetry, or if the rattle is near electrical wiring, stop and call a plumber. A professional can locate the pipe behind finishes and secure it without opening walls unnecessarily.
What Not to Do
- Don’t open walls or cut into finished surfaces yourself just to chase the sound. That can cause unnecessary damage.
- Don’t wedge random shims or jam pieces of wood blindly between a pipe and the wall. Improper shimming can damage the pipe or fittings.
- If the rattle is near wiring or finished ceilings, don’t try to trace the pipe by drilling or slicing drywall—let a plumber locate the pipe first.
- Don’t hammer or force fittings; don’t overtighten compression nuts or straps.
When to Call a Professional
- If you cannot safely access the pipe run because it is behind finished walls, ceilings, or built-in cabinets.
- If the noise is accompanied by leaks, visible movement of the finish, or repeated loud banging (which can indicate serious water hammer).
- If the rattling is close to electrical wiring or you are unsure where the pipe runs—call a plumber to locate and secure the line properly.
- If you prefer a safe, permanent fix: a plumber can install proper clamps, nail plates, or water-hammer arrestors and secure the run without damaging finishes.
Safety Notes
- Turn off the water at the shutoff valve before working on or under the sink.
- Avoid drilling or cutting into walls unless you are certain of what’s behind them—wires and pipes can be damaged.
- If you see active leaking, soften drywall, or electrical arcing, stop and call a professional immediately.
- When in doubt about wiring or structural elements near the pipe run, hire a licensed tradesperson.
Common Homeowner Questions
- Is this an emergency? Usually not immediate, but call a plumber if you see leaks, repeated banging, or damage to finishes.
- Can I fix it myself? Sometimes—tightening visible straps under the sink can help. If the pipe is behind finishes or near wiring, hire a pro.
- Will the rattle damage the wall? Continuous vibration over time can loosen finishes or cause cracking; securing the pipe prevents long-term damage.
For more related articles, see the Rattling Pipes Inside Walls hub.