How Do Garbage Disposals Work?

This month we’ve been talking a bit about garbage disposals and how to keep them clean but how do they even work? It is a fair question! For most folks it’s just enough to know they do work, but knowing how they work can help you address problems early, and how to get the most out of your garbage disposal. So. This time on the Economy Plumbing Services Blog we’re answering just how garbage disposals work!

How Do Garbage Disposals Work?

The garbage disposal is made up of a few parts that work together to grind up food waste into a slurry that’s safe to run through a drain pipe. Here are the various parts and how they work.

The Hopper Chamber

This is the hollow cylinder that sits beneath your sink and houses the disposal proper. There are two portions – the upper and lower chambers. Food enters through the drain into the upper hopper chamber before it’s shredded up.

The lower hopper is insulated, and holds the motor to the disposal. It also connects to the waste line. After the food is ground up it moves through one the top to the lower chamber on it’s way out of the drain pipe. The lower hopper will also have a reset button on the bottom.

The Flywheel and the Shredded Ring

The shredder ring sits between the upper and lower chambers, right smack dab in the center of the disposal. The shredder ring has inner walls made up of sharp grooves that help grind up and break down food. If you think of it like a cheese grater you’re halfway there! The flywheel is a rotating metal turntable that’s attached to the bottom of the shredder ring. It prevents any food from entering the lower hopper chamber until it’s small enough to safely go through the sides of the shredder ring and down the drain. The flywheel connects to the next pieces in the disposal unit, the motor and impellers.

The Motor and Impellers

It shouldn’t come as any surprise that garbage disposals have motors. After all, when you flick the switch and hear it rev up there’s got to be something powering those grinding features right? A typical motor generates between a half and ¾ horsepower of force. The motor rotates the flywheel and the impelleers that are attached it, rotating them up to two thousand times per minute (or 2000 RPM). When you think of a garbage disposal you probably think it has some sort of blade in there right? That’s why you don’t want your hands in it right? Those ‘blades’ are the impellers. They fling food chunks into the shredder ring which breaks up the chunk so food. This happens back and forther until the food chunks are small enough to go past the shredder ring and down the waste line.

The Waste Line Connector

The waste line connector, housed in the lower hopper chamber is the final section of the disposal. From here the shredded, ground-up food particles fall and are washed out with the water, leading into the drain pipe.

The Power Cord

Because your garbage disposal needs electricity to power its motor, there is a power cord attached to it. This plugs in a normal outlet that is in the wall under your sink. 

What Breaks When It Breaks

Problem: It Won’t Start

Chances are this is an electricity problem, not a problem with the disposal proper. Take a look at the reset button. Press it and try turning your disposal on again. Sometimes a simple reset is all that’s needed. If that still doesn’t fix it take a look at the plug and the outlet. 

When it comes to electricity, you usually don’t want to do any of these jobs yourself as it’s more dangerous than other at-home DIY jobs. 

Problem: It’s Jammed

If the disposal is jammed it’s probable that the impellers are stuck. Unplug the disposal from the wall to prevent any accidents and then look for a hole at the bottom of the lower hopper chamber. It should be hex-shaped. Take a hex wrench that fits it and put it into the hole then work the wrench back and forth to free the impellers.

Problem: It Leaks

With all the connecting parts and pieces in your garbage disposal there are many places a leak can happen. Figure out where the leak is coming from, then try and tight any loose pieces. There’s a chance that a gasket has worn down in the connections and water is leaking past it. If the water is dripping from the button of your lower hopper chamber, like where the reset button is, bad news. That disposal is toast. The gasket that keeps water where it should has been worn down and water has run through the electronic components of your disposal.

Time to call a professional for a new disposal unit.

Problem: It Won’t Grind

Make sure you’re running water while you use the disposal and that you’re only putting foodwaste down the drain that the disposal can handle. If those two things are true and the disposal still isn’t breaking down the food then it’s likely the impellers and/or shredder ring have dulled. If this is the case then the option is to either replace those components individually or take a look at replacing the whole disposal. 

Having trouble with your garbage disposal? Need help troubleshooting problems or just need a new unit entirely? You know what to do.


If water runs through it or to it, we do it!