Why Is My Garbage Disposal Not Working?
A garbage disposal that stops working is one of those problems that tends to happen at the worst possible moment - right before you need the sink. The good news is that most disposal failures follow a short list of patterns, and several of them are things you can fix yourself in a few minutes.
Here is how to work through the most common causes, starting with the simplest.
Key takeaways:
Start with the reset button on the bottom of the unit before anything else
A humming disposal that will not spin is jammed - use a hex key on the bottom of the unit to free it
No power at all usually points to the reset button, a tripped GFCI outlet, or the circuit breaker
A disposal that drains slowly has a clog in the drain line, not a motor problem - skip the liquid drain cleaner
Leaks from the bottom of the unit mean internal seal failure and the disposal needs to be replaced
Loud grinding or rattling usually means something is in the chamber - use tongs, never your hand
Grease, fibrous foods, starchy foods, and bones are the most common causes of disposal problems
Start Here: The Reset Button
Before anything else, check the reset button on the bottom of the disposal unit. It is a small red or black button, and it pops out automatically when the motor gets overloaded or overheats.
Press it firmly until you feel it click, then try running the disposal again. If it trips again immediately or will not stay in, there is something else going on - keep reading.
1. The Disposal Is Humming but Not Spinning
A humming disposal that does not spin is one of the most common calls we get. The motor is getting power, but the grinding plate is jammed and cannot turn.
The fix is to manually free the jam:
Turn off the disposal and unplug it from the outlet under the sink (or flip the breaker if it is hardwired)
Look under the unit for a hex key socket in the center - most disposals include a small hex wrench for this
Insert a 1/4-inch hex key and work it back and forth until the plate turns freely
If you do not have a hex key, a wooden broom handle inserted into the drain opening from above can also break the jam loose - never use your hand
Once the plate moves freely, plug the unit back in, press the reset button, and run cold water before turning it on.
In Arizona homes, hard water mineral buildup can contribute to disposal jams over time, especially in older units. If you are clearing jams regularly, the disposal may be nearing the end of its useful life.
2. The Disposal Has No Power at All
If you flip the switch and get nothing - no hum, no movement, no sound - the problem is almost certainly electrical.
Check in this order:
Reset button: Try it again if you have not already
Under-sink outlet: Many disposals plug into a switched outlet under the sink. Check that the plug is fully seated and that the outlet itself has power (test it with a phone charger or lamp)
GFCI outlet: If the outlet under the sink is a GFCI type (with test and reset buttons on the face), press the reset button on the outlet itself - it may have tripped independently of the disposal's own reset
Circuit breaker: Go to your panel and look for a tripped breaker. Reset it if needed
If all of that checks out and the disposal still will not power on, the motor or internal wiring has likely failed.
3. The Disposal Turns On but Drains Slowly
If the motor is running fine but water backs up into the sink, the problem is a clog in the drain line rather than the disposal itself.
The disposal grinds food waste, but it cannot clear a backed-up drain pipe on its own. Grease, fibrous food scraps, and accumulated debris can pack into the line between the disposal and the p-trap or further down.
Do not use liquid drain cleaner in a disposal. It can damage the seals and rubber components inside the unit.
Instead:
Try plunging the sink with standing water in the basin to push the clog through
Check the p-trap under the sink for blockage - it is a quick disconnect on most setups
If the clog is further down the line, a drain snake will reach it
If both the kitchen sink and a nearby dishwasher are backing up at the same time, the blockage is likely past the point where the drain lines join, and you may need a plumber to clear it from further down.
4. The Disposal Leaks
Leaks from a disposal usually come from one of three places:
Top of the unit (sink flange): The mounting ring or plumber's putty seal has failed. This is a common issue in older installations and in areas with hard water, where mineral deposits work into the seal over time.
Side of the unit (dishwasher or drain line connection): A hose clamp has loosened or a gasket has worn out.
Bottom of the unit: This usually means an internal seal has failed. At that point the disposal itself needs to be replaced rather than repaired.
Leaks from the bottom are worth noting because they can go undetected for a while in the cabinet under the sink. If you notice water damage, warped wood, or a musty smell under the sink, check the disposal before assuming there is a pipe problem.
5. The Disposal Makes a Loud Grinding or Rattling Noise
A grinding or rattling noise that is louder than usual usually means something is in the grinding chamber that should not be there. Small bones, fruit pits, bottle caps, and silverware all find their way in.
Turn off and unplug the disposal, then use tongs or needle-nose pliers to remove whatever is in there. Never reach in with your hand, even when the unit is off.
If the noise persists after clearing the chamber, the grinding components inside may be worn or damaged. On a unit that is more than 10 to 12 years old, replacement usually makes more sense than repair.
What Not to Put Down a Disposal
A lot of disposal problems are preventable. These are the items that cause the most damage:
Grease, oil, and fat (solidify in the drain line)
Fibrous foods like celery, artichokes, and corn husks (wrap around the grinding plate)
Starchy foods like pasta, rice, and potato peels (expand and create paste-like clogs)
Bones and fruit pits (can jam or damage the grinding components)
Coffee grounds (accumulate in the drain line over time)
Running cold water for 15 to 20 seconds before and after using the disposal helps flush debris through the line and extends the life of the unit.
When to Call a Plumber
Most disposal issues - jams, tripped resets, and minor leaks at fittings - are manageable on your own. Call a plumber when:
The motor hums but the jam will not clear with a hex key
The unit has no power and you have ruled out every electrical cause
There is water damage under the sink and you are not sure where it is coming from
The disposal is leaking from the bottom
Drains in multiple fixtures are backing up at the same time
Superstition Plumbing has served Mesa and the East Valley for 45 years. If your disposal is beyond a quick fix, our team can diagnose the problem and give you a straight answer on whether repair or replacement makes more sense - no pressure either way.
