Quick Answer:
If your garbage disposal hums while the sink water rises, the unit is likely stalled by a jam or the outlet pipe is partially blocked. Press the reset button, then safely check the disposal outlet and drain path for obstructions before trying the unit again.
Why This Happens
- A humming sound usually means the motor is getting power but the blades can’t turn. That commonly happens when food or a foreign object wedges the impellers.
- If the outlet immediately after the disposal or the trap is partially blocked, water can back up into the sink while the disposal struggles to clear the load.
- If the issue only happens under certain conditions it can point to different causes—see Backup occurs when disposal slows and Backup only when grinding food for related scenarios.
Step-by-Step What to Do
1. Stop and turn off the power
Shut off the disposal at the wall switch. For extra safety, switch off the circuit breaker that feeds the disposal or unplug the unit if accessible.
2. Press the reset button
Locate the red reset button on the bottom or side of the disposal and press it once. This can restore the internal overload switch if it tripped. If the button pops back out immediately or the unit still hums, don’t keep pressing it—proceed to the next checks.
3. Check for a jam from above
- Keep the power off. Use a flashlight to look down the sink flange for visible items.
- Use long pliers or tongs to remove any visible debris—do not put your hand into the disposal even if it’s off unless you’ve confirmed the breaker is off and you follow safety steps below.
4. Free the grinding mechanism from below (if applicable)
Many disposals have a hex socket at the bottom for a manual crank. With power off, insert the manufacturer’s wrench or a hex key and turn it back and forth to dislodge jams. If the impeller begins to turn freely, reset and test briefly with water running.
5. Inspect the disposal outlet and trap
- If the sink still fills, place a bucket under the trap, loosen the slip nuts, and inspect the trap for clogs. Remove and clear it if needed.
- Also check the short horizontal section of drain just after the trap; partial blockages here commonly cause slow drainage while the disposal hums.
6. Test the unit carefully
Restore power, run a steady stream of cold water, and turn on the disposal briefly. If water still backs up or the disposal hums without turning, stop and proceed to professional help.
What Not to Do
- Do not keep resetting a humming disposal without checking for blockage.
- Do not put your hand into the disposal while the power could be on.
- Do not use drain-cleaning chemicals in or near the disposal; they can damage components and create hazardous reactions.
When to Call a Professional
- If the disposal hums but will not turn free after you’ve checked and cleared visible obstructions.
- If water continues to back up after clearing the trap and outlet, suggesting a deeper clog or a damaged unit.
- If you’re uncomfortable removing the trap or working under the sink, or if the unit leaks or shows electrical faults.
Safety Notes
- Always cut power at the switch and, for best safety, at the breaker before inserting tools or hands into the disposal or working under the sink.
- Use pliers, tongs, or a hex wrench rather than bare hands to remove objects.
- Wear eye protection and gloves when working with plumbing or debris.
Common Homeowner Questions
- Why did the disposal start humming?
A jammed impeller or a motor overload—usually from something stuck in the grinding chamber. - Will pressing reset always fix it?
No. Reset can restore power after an overload, but it won’t remove a physical blockage; you must clear the obstruction first. - Can I remove the trap myself?
Yes, if you’re comfortable using basic tools; put a bucket under the trap, loosen slip nuts, and inspect—otherwise call a plumber.