How Do Garbage Disposals Work?

Bad food leftovers? Putting trash in a garbage bag and tossing it out of the house isn’t always the best method of disposal. To pulverize discarded food for better and more convenient disposal of food waste, you could use a garbage disposal next to your kitchen sink.

Garbage disposal comes in handy if you’re looking for a more efficient way of decluttering your pantry. This device chews or grinds all your food scraps and flushes them down the drainage with a strong stream of water.

How Do Garbage Disposals Work featured photo

Many households use garbage disposals, but very few understand how they function. In case you’re one of them, I’ll explain to you how a garbage disposal works. What are the problems you might encounter with it and how to mitigate them?

What Is a Garbage Disposal?

Invented by John W. Hammes in 1927, a garbage disposal is a drain-connected appliance that shreds food scraps into pieces. It chews the food chunks with its built-in blade. As soon as the food waste is ground up, it can pass through the plumbing system safely.

It reduces waste materials which allow for faster biodegradation — a natural process by which organic matters are broken down by microorganisms. It’s an environment-friendly appliance that cuts down greenhouse gas emissions from landfills, creating less methane.

You’ll find a garbage disposal in most American homes. It has become a necessary kitchen appliance in every household. Garbage disposals may feature an auto-reverse function to prevent clogs. It may also have a greater horsepower engine. This can cut through bones and other hard items. But it depends on the model you have.

Where Is It Installed?

A garbage disposal is installed under your kitchen sink. The hollow cylinder beneath your sink houses the disposal’s engine including all its mechanical components. It’s powered by a plug that connects to a standard wall outlet. The power line from the plug to the disposal’s bottom is most likely visible.

Components of a Garbage Disposal

Now, let’s take a look at the basic components of a garbage disposal. Each part plays an important role in ensuring your food waste gets flushed down the drain smoothly.

Garbage Disposal Exploded View

Splash Guard

Splash guards are rubber flaps that surround the edges of your sink drain. It’s the rounded thing you see when you’re gazing at your garbage disposal while it’s running. The rubber flaps are why the water and crushed food don’t splash right back into your sink. It’s also where you should dispose of your food waste.

Flywheel, Shredder Ring, and Impellers

The shredder ring and the flywheel are located within the upper hopper. On the sides of the flywheel, you’ll find two impellers. There’s also an insulation motor at the base of your disposal that spins the shredder wheel, a sharp piece of metal with grooves and teeth.

Whatever food or water you place in the upper hopper, the centrifugal takes care of it. It spins the food, forcing them into the shredder ring. Then, they are shoved up onto the grind ring by the impellers as the flywheel spins. The motor spins the flywheel and the impellers at up to 2000 RPM.

Hopper Chamber

A hopper chamber is a hollow cylinder with two sections: upper and lower chambers. Before even being shredded, food that reaches the disposal gathers in the upper hopper chamber.

Your garbage disposal’s motor is in the lower hopper chamber, which is the insulation. The waste pipe is also connected to this part. Food travels from one portion of the lower hopper chamber on its path out to the drain pipe. This happens after your garbage disposal grinds it up.

When you throw food down the drain, ensure that the garbage disposal is running while water is flowing into the upper hopper chamber.

Waste Line

The water pouring down the hopper now moves the organic waste into the pipe, through the p-trap. The water from your kitchen tap flushes the food bits down the holes in the ring, out of the chamber. And then into the pipe, while the food material is crushed into small chunks. The ground-up foods will then end up in your home’s septic tank.

How Do Garbage Disposals Work?

Woman disposing garbage

But seriously, how does a garbage disposal work?

The garbage disposal uses a motor. It can be hardwired or plugged into a 120-volt box or socket. The unit is normally installed at the rear of your sink cabinet. Also, most garbage disposals are compatible with standard drain outlets. Local safety rules may dictate the space between the switch and the sink. But the greater the gap, the safer.

Once you start the garbage disposal, the impeller spins quickly, driving the food scraps against the exterior wall of the grinding chamber. The food is shredded into little pieces that are subsequently flushed down by the water by holes in the chamber wall.

Disposals do feature two dull metal teeth on the impeller plate, but their blades aren’t sharp. It’s the reason why you won’t need to sharpen them. They are designed dull.

Dishwashing water also passes through your garbage disposal. It grinds up all large items as they enter the drain pipe.

What Causes a Garbage Disposal To Break

The very first step in repairing a garbage disposal that won’t operate is determining what’s wrong with it. Here are some of the reasons why your unit won’t work.

It doesn’t start

If your garbage disposal won’t start, it’s most likely an electrical fault. On the bottom of its lower hopper chamber, locate the reset option. You can restart the unit by pressing the button. If this doesn’t help, check to see if the outlet where the disposal is connected is faulty.

Do a little troubleshoot

Doing a little troubleshooting can’t hurt. By doing this, it could save you money spent on repair visits or buying an expensive new machine.

Repair if clogged

The majority of garbage disposal issues are caused by blockages. A clogged garbage disposal isn’t hard to remedy. Throwing food items that aren’t intended for garbage disposal causes clogs. But they also occur in the drain pipe, and it’s quite common.

The best approach to avoid clogging is to get food pieces out of your garbage disposal and discard them. Neglecting a blockage and letting the garbage disposal run continuously can wear out the motor. 


One of the reasons your garbage disposal stopped working is probably because the impellers are jammed. To fix this, you must first unplug the unit. At the bottom of the lower hopper chamber, check on the hex-shaped hole. You’ll see this hole in many garbage disposal units. Then unjam the impellers by inserting the wrench into the hole and twist it back and forth.


Your garbage disposal consists of a number of interconnected pieces. Leaks may arise in either of these components. Determine where the leakage comes from and fix the connecting parts if necessary. Using a screwdriver is handy for tightening the screws.

It won’t grind

Its impellers or shredder ring have blunted. And perhaps you’ve been throwing food items in the dishwasher that are not meant to get down there. You have the option of replacing a specific component. It’s important to get your garbage disposal from a manufacturer that provides a lengthy warranty. This won’t have a hard time finding a replacement.

Removing and Installing

If you’re replacing the garbage disposal that’s broken, you’ll need to remove it first. There are a lot of models that let you simply remove the motor unit from your sink unit. Since the motor is the heaviest component of the disposal, removing it first will make the dismantling process easier.

Mounting garbage disposal is rather simple. But it does involve basic plumbing and electrical wiring knowledge. If you’re not confident with the skills you have, you may call a plumber.

Never Put These Things in a Garbage Disposal

Most people see a set of teeth underneath their sink, much like a blender. Where it liquifies the food scraps that go down the sewer. It’s one of the common misconceptions people tend to have. But the thing is, you can’t just throw anything down there.

Also, your garbage disposal is not the same as your trashcan. It’s not like all food scraps and fluids should be flushed down the drain pipes. You’ll avoid clogs and waste jams if you understand which foods should be thrown out and which ones should be put in your garbage disposal.

Grease and Oil

Grease can quickly harden and block your plumbing because it thickens as it cools. After cooking, you must pour hot grease or oil onto an empty milk carton or any container you won’t use anymore. Then, throw it away once it’s cooled and hardened.

Pits, Seeds, and Coffee Grounds

Some seeds may be small, but they can cause your garbage disposal to jam. Hard and round items will not grind well in your garbage disposal. Even tiny pits, such as those from olives, might clog the drainage if they become trapped in the disposal.

You should also avoid dumping coffee grounds down your garbage disposal after brewing. Another reason for this is that coffee grounds can become lodged in the trap of your garbage disposal. And it can slide into your pipes like sediments.

Egg Shells

Egg shells have a thin membrane that can wrap around the blades of your garbage disposal. Plus, the shells are hard. You’ll need to toss the eggshells in the trash or compost them rather than just dumping them down the sink.

Pasta and Rice

Rice and pasta both expand when submerged. These food items can accumulate in the trap of your garbage disposal. The inevitable eventually. They can clog your garbage disposal over time.

Fibrous Veggies Like Celery

Stringy, fibrous, or starchy vegetables like celery and asparagus can wrap around the blade of your garbage disposal. And this can form clogs.

The Dos and Don’ts

Considering that you now understand how a garbage disposal works, how to fix things, and what you should and should not put in there. There are also some more notes you need to take.


  • When operating your garbage disposal, always run cold water through it.
  • You can throw food waste that’s easily crushed up like leftover veggies in your garbage disposal.
  • Before you use the garbage disposal, ensure it’s plugged in.
  • Whenever it’s processing food, leave it for at least 30 seconds.
  • Before performing any repair at your disposal, you should unplug it from an outlet for safety.
  • Keep throwing food items that shouldn’t go in the garbage disposal into your trash and recycle bins. It’s a useful machine, but it won’t eat everything. It won’t be able to take the place of your rubbish can.
  • Keep your garbage disposal clean by draining it or putting a mixture of diluted dish detergent and water through it on a regular basis. This is to avoid junk from accumulating in the components.
  • Cutting up large food items is a smart strategy to avoid clogging or blocking your garbage disposal. Making sure the waste you throw into it is in little bits. It will be easier for the disposal to chew them.


  • Unless it’s unplugged, and never ever, under no circumstances, stick your hands into your garbage disposer.
  • Don’t try to grind grease, bones, veggie peels, fruit pits, and other solid foods in your garbage disposal.
  • Don’t try to shove food into the disposal by squeezing it.
  • Don’t turn off the sink while the garbage disposal is running.
  • Don’t put utensils or other equipment down the disposal while it’s plugged and running.
  • Make no attempt to sharpen the blades. Garbage disposal impellers are dull, so there’s no point in trying to sharpen them.
  • Bleach and other harsh chemicals should be avoided. Harsh chemicals can corrode the inner components, causing them to work less than optimally.
  • Don’t dump excessively down the garbage disposal in one go. Garbage disposals are designed to process lesser amounts of food waste.

Garbage Disposal FAQs

Where does the waste go from a garbage disposal?

Ground-up food wastes go to treatment plants. It’s where anaerobic digesters collect them. And then turn the methane gas emitted from degradation into power or biofuels.

Is it bad to put food down the garbage disposal?

It’s not. But you shouldn’t use garbage disposals to dispose of huge volumes of food waste. Dumping small amounts at a time while running cold water helps the food scraps flow smoothly down the plumbing. But keep in mind that they can pile up in pipelines which results in clogs.

Can banana peels go in the garbage disposal?

You can throw banana peels down the garbage disposal. But make sure you remove any stickers first. As these will likely adhere to the shredding blades. Or worse, they can get stuck inside the pipes.

Can you run the garbage disposal while the dishwasher is on?

You can run the garbage disposal while your dishwasher is in use as long as they are both correctly installed. But keep in mind that using both appliances at the same time could still pose problems. Especially if your system is old, damaged, or poorly set up.

Should you run hot or cold water down the garbage disposal?

When your garbage disposal is in use, you can run cool water through it. Although it’s best to stop throwing fats, oils, or grease down the drain, certain food waste contains fat that you can’t separate. So, running cool or cold water may not be a good practice. Oil can thicken and end up clogging your disposal.

Final Say

Understanding the basics of your garbage disposal, how it works and what causes it to break down will assist you in maintaining it. As well as ensuring that it continues to function for many years to come. This appliance can be expensive. So, ensure you take note of the do’s and don’ts to prolong the life of your garbage disposal.