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A garbage disposal is a simple machine: a motor spins a plate with two loose lugs that fling food against a grinding ring. When it stops working, the cause is nearly always something stuck, a tripped overload, or a worn seal. Almost none of it needs a plumber, but all of it needs the rule that comes first.
The rule
Never put your hand into the disposal. Not when it is switched off, not when it is unplugged. Use tongs or pliers to remove anything, and use the hex key for jams. If you cannot fix it with tools from the outside, that is what the plumber is for.
It hums but does not turn
The motor is running but the plate is jammed.
- Switch it off at the wall switch and, if you can reach it, unplug it under the sink or switch off its breaker.
- Find the hex socket in the center of the underside of the unit. Insert the hex key that came with the disposal, or a quarter-inch hex key, and work it back and forth until the plate turns freely a full circle.
- Look down the drain with a flashlight, and remove whatever caused the jam with tongs. Bottle caps, fruit pits, bones and a stray spoon are the usual culprits.
- Press the red reset button on the underside, which will have popped out when the motor overloaded.
- Restore the power, run cold water, and switch it on.
Nothing happens at all
- Press the reset button on the underside.
- Check that the unit is plugged in. Many are plugged into an outlet under the sink that is controlled by the wall switch, and the plug works loose.
- Check the breaker.
- If it still does nothing, and the motor does not hum, the motor or the switch has failed. A disposal more than about ten years old is usually not worth repairing.
It runs but drains slowly
The grinding chamber or the drain pipe is clogged with fibrous or starchy waste. Switch off and unplug, then plunge the sink with a flat plunger, holding a wet cloth over the other bowl if there is one. Never pour chemical drain cleaner into a disposal. If plunging does not clear it, the trap under the sink can be removed and cleaned as with any sink.
It leaks
Find where the water is coming from, with a dry paper towel and the water running.
- From the top, where it meets the sink: the mounting ring has loosened or its putty has failed. Tightening the mounting screws often fixes it; otherwise the unit has to come off and be resealed.
- From the side, at the dishwasher hose or the drain pipe: tighten the clamp or the drain flange bolts, and replace the rubber gasket if needed.
- From the bottom of the unit: the internal seal has failed. That is the end of the disposal. Replace it.
It smells
Grind a tray of ice cubes with a handful of coarse salt, then run cold water. Follow with cut-up citrus peel. Clean the underside of the black rubber splash guard with a brush, which is where most of the smell lives. Do this monthly.
Using it so it lasts
- Run cold water before, during and for fifteen seconds after. Cold water keeps grease solid so that it is chopped and flushed rather than coating the pipes.
- Feed it gradually, not all at once.
- Keep out fibrous vegetables such as celery and corn husks, large quantities of potato or rice, coffee grounds, eggshells, bones, grease and anything that is not food.
- Run it regularly, even with nothing in it, to prevent rust and seizing.
Replacing a disposal
A like-for-like replacement is a job many homeowners do, and a plumber does it in about an hour. Choose at least a half-horsepower model for a family, and one with a stainless grinding chamber if you want it to last.
When to call a plumber
- A leak from the bottom of the unit
- A leak at the sink flange that tightening does not stop
- Any electrical fault: a switch that sparks, a unit that trips the breaker
- Replacement, if you would rather not work in the cabinet
Find a licensed plumber near your town.