How to Tell If Your Garbage Disposal Is Bad (or Just Jammed)

Here is how to tell which one you have, in the order a plumber would check.

Graphic: summary of this guide, made by our team from the cited sources.

Symptom check: fixable or time to replace?

What you notice	What it usually means	Try this first	Points to replacement when
Hums but does not grind	Turntable jammed by a bone, pit or utensil	Power off, turn it with the wrench, press reset	It still will not turn after the wrench and three rounds of grinding bones
Nothing at all, no hum	Tripped reset, tripped breaker or a dead switch or outlet	Press the red button, check the breaker, test the outlet with a lamp	The lamp works with the switch but the disposal does not
Shuts off during use	Overload protector tripping from a jam or a long run	Clear the jam, wait, press reset	It keeps tripping with nothing jammed
Water stays in the sink	Clog in the drain line past the disposal	Plunge with about 4 inches of water in the sink	Not a disposal failure
Bad smell	Food buildup under the rubber baffle	Scrub the baffle, run warm water and baking soda	Not a disposal failure
Rattling or loud vibration	Object inside, loose plumbing or an unlocked lower mounting ring	Remove the object with tongs, tighten connections, relock the ring	Grinding noise continues with the chamber empty
Leak at the top, side elbow or dishwasher hose	Seal, screws, clamp or gasket	Tighten or replace the gasket or clamp	Not usually a disposal failure
Leak through the body or at the motor joint	Internal seal failure	Confirm water is not running down from above	Yes, if confirmed

The table is built from the troubleshooting pages of InSinkErator, Waste King and Moen linked through this guide. Work through the sections below before you buy anything.

"Is my garbage disposal full?"

No. A disposal is not a storage bin. InSinkErator explains that it has no blades at all: small lugs throw the food against a fixed grind ring, which breaks it into very fine particles that flush away with the water. Nothing is supposed to stay inside.

When people say the disposal is "full," they usually mean water is sitting in the sink. InSinkErator's clog test is simple: turn the disposal on and look at the water. If you see a whirlpool, the disposal is spinning and the clogged drain line is the problem, not the unit. If there is no whirlpool and the motor is running, it is jammed. If it is not running at all, go to the power checks below.

To clear a drain-line clog, InSinkErator says to put about 4 inches (10 cm) of water in the sink, set a plunger over the disposal opening, press down slowly, then pull up hard. Once it drains, run water and the disposal for a minute or two. If both sides of a double sink back up, the clog is further down the line; our guide to why both sides of a kitchen sink drain slowly covers that.

It hums but will not grind: clear the jam

A hum with no grinding is the classic jam. Waste King's manual says it can mean the turntable is not rotating, usually because something is lodged between the turntable and the grind ring. Waste King also lists three signs of a jam in its FAQ: a different noise from the normal grind sound, a mess at the splash guard after you run it, and a rotten-food smell from the opening.

InSinkErator's jam steps:

1. Turn the disposal switch off. Never put your hand in the disposal.
2. Find the hole in the center of the bottom of the unit. Insert the small crank-shaped wrench that came with it (about 4 inches long), or a standard 1/4-inch Allen wrench.
3. Work it back and forth in both directions until it turns easily in full circles. Some force is fine; InSinkErator says the wrench is designed to bend before the disposal is damaged.
4. Shine a flashlight inside and lift out anything you see with tongs or pliers, paying attention to the small teeth around the outer edge.
5. Press the red reset button on the bottom, then run cold water and test it.

For its Builder Series, Amana and ES units, InSinkErator gives a different method: turn off the disposal and the water, then rotate the turntable in either direction from above with a wooden spoon. Waste King's FAQ allows either a wooden spoon or its unjamming wrench.

If the impellers still feel stiff, InSinkErator's won't-grind guide says to check that the two swiveling impellers move when you push them with a spoon handle. If they do not, run three or four beef round-steak bones or fruit pits through it with water (chicken bones do not work well). If three tries fail, the disposal may need service.

It does nothing at all: check power before you blame the motor

1. Reset button. InSinkErator says the overload protector shuts the unit off when it is jammed, runs a very long time, or has another issue. It is a small red square button on the bottom, facing the floor. When tripped, it sits about 1/4 inch (5 mm) lower than normal. Press it gently. If it will not stay in, wait ten minutes and try again (resetting a disposal).
2. EZ Connect models. These have an automatic overload switch instead. Turn the wall switch off, or unplug a push-button model, and let it cool for up to 20 minutes.
3. Breaker or fuse. Switch the breaker off and back on, or replace the fuse.
4. Switch and outlet test. Plug a lamp, night light or hair dryer into the disposal's outlet and flip the switch. InSinkErator's won't-turn-on guide is clear about the result: if the test device turns on and off with the switch, the disposal needs service. If it does not, the outlet or switch is the problem and you need an electrician.

That lamp test is the cleanest "is it dead?" answer you can get at home. Power reaching the outlet plus a cold, silent disposal with nothing jammed means the motor or its internal switch has failed. Waste King's manual reaches the same conclusion: if the wiring and electrical parts are intact, the unit may have an internal problem that needs service or replacement.

Where it leaks decides repair or replace

Leaks are the symptom people most often read as "it's dead." Usually it is not. First find the exact spot. InSinkErator's leak guide suggests taping newspaper flat on the cabinet floor, filling the sink, pulling the stopper and running the disposal to see where drips land. Moen's version wraps paper towels around the sink flange, the discharge elbow and the dishwasher connector, then checks which one gets wet.

• Top, at the sink flange or mounting ring. Waste King lists improper seating of the sink flange and a defective or badly installed cushion mount. InSinkErator's mounting-assembly check is to confirm the mount is assembled correctly, the locking ring is rotated fully to the right and all three screws are tight. On a new install, excess plumber's putty under the flange can also cause it. Fixable.
• Side, at the discharge elbow. InSinkErator's discharge checklist: make sure the nut or bolts are tight, check the gasket for debris, cracks or rips, and look for cracks in the elbow. Waste King's manual adds the elbow flange screws. Fixable.
• Dishwasher inlet. Check that the hose clamp is tight and any hose adapter is intact. On a new hookup, InSinkErator says the knockout plug inside the inlet must have been removed. Fixable.
• Bottom. This is the tricky one. Moen points out that a damaged discharge gasket can let water travel down between the outer shell and the disposal and drip out by the cover plate on the bottom. So a "bottom leak" can be a cheap gasket. Dry everything and check the elbow before you decide.
• Through the wall of the body, or at the motor joint. If you have confirmed the water is not running down from the top, InSinkErator says to contact them for help, and Waste King's manual says a leak anywhere other than the top, elbow or dishwasher hose may be an internal problem that requires service or replacement. This is the true "replace it" sign for most homeowners.

Bad smell: almost never a broken disposal

InSinkErator says an odor is usually food buildup caused by not running enough water during and after use. Its odor fix: reach through the opening and scrub the underside of the rubber baffle and the upper lip of the grind chamber with a scouring pad, then fill the sink halfway with warm water mixed with 1/4 cup of baking soda, pull the stopper and run the disposal. Waste King gives nearly the same advice for its splash guard.

If the smell is still there after cleaning, it may be coming from the drain under the disposal instead. Our guide to cleaning a smelly P-trap under the kitchen sink walks through that.

Warranty: the best clue to how long yours should last

No manufacturer we checked publishes an expected lifespan. What they do publish is warranty length, which is a fair guide to how long the maker expects a model to hold up.

Graphic: made by our team from InSinkErator's warranty-by-series figures (linked above).

Waste King says its coverage varies by model, and its manual notes the warranty does not cover jams or grinding things that are not food. The model and serial number are on the label on the bottom of the disposal, so check it before you pay for a repair. A unit still under warranty that has a quality problem may be fixed at no charge: InSinkErator says it may pay an authorized service center to repair it in your home.

Habits that prevent the next "bad disposal" scare

• Run a moderate flow of cold water while grinding and for a few seconds after. InSinkErator says to avoid hot water while grinding, though it is fine to drain hot water between uses.
• Never pour grease or fat into the disposal or the drain.
• On a Standard Series InSinkErator, skip stringy, fibrous scraps such as banana peels, celery and rhubarb; the company says that series cannot grind them.
• Keep large whole bones and metal such as bottle caps out of the chamber, as Waste King's manual warns, and leave the stopper in when the disposal is not in use so nothing falls in.
• Never use chemical drain cleaners in a disposal. Waste King says they cause serious corrosion of metal parts and void all warranties.

If the drain keeps backing up even with a healthy disposal, the problem is in the pipes. Our guide to why a drain keeps clogging explains how to find the real cause.

When to call a plumber or electrician

• The lamp test works with the switch but the disposal stays silent: plumber or a replacement unit.
• The lamp test fails: electrician, since the problem is the switch or outlet.
• Water leaks through the body or at the motor joint after you have ruled out the top and the elbow: replacement, or a warranty claim if it is still covered.
• The disposal keeps tripping its reset button with nothing jammed inside.
• You are not comfortable working under the sink near wiring. Always switch it off first, and keep your hands out of the chamber.