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How Sharp Are The Garbage Disposal Blades?


You scrape your plate into the kitchen sink, run the water, and turn on the garbage disposal. You may expect that the spinning blades within the disposal chop the cooked carrots and chicken strips up into small bits, shredding it much like a blender or food processor would. And that may lead you to wonder just how sharp those blades actually are, and what types of food you should avoid.

There are several misconceptions about what can and what cannot go into the kitchen drain and garbage disposal. And one of the biggest misconceptions of all about garbage disposals is the idea that they have sharp blades in the first place. Read on to learn how your garbage disposal really works, and find out why certain items simply do not belong here.


If you’ve always pictured the garbage disposal to have sharp, rotating blades that cut through your leftover food items, think again. This is a common misconception fueled, in part, by the belief that a garbage disposal’s parts look like a blender’s.

Rather, your garbage disposal has rotating impellers, which move quickly and with force to grind up food and break it into bits. Here’s a better look at how the parts work together to break down food.

  • Impellers are mounted on a plate that spins when the disposal motor starts up.
  • Centrifugal force works to force food particles against a grind ring at the bottom of the unit.
  • The force of the particles against the grind ring breaks food down into bits.
  • Running water helps these particles to flow through the grind ring, into your drainpipes, and out to the sewer system.


Now that you understand how a garbage disposal works, it’s a lot easier to see that certain food items simply do not belong in the disposal.

  • Trash – Of course, plastic and paper wrappers and the like do not belong in the disposal. They will not be properly broken up in the disposal and may cause sewer and drain problems later on.
  • Fibrous food items – Anything with too many fibers—food you would considered “stringy” or like paper does not belong in the disposal unit. Why? The fibrous food items can wrap around the disposal impellers, causing them to stop up and hamming the disposal motor. This category includes things like celery, asparagus, and onion skins.
  • Hard food items – A good rule of thumb: if you could not chew it with your teeth, it doesn’t belong in the disposal. This includes meat bones, fruit pits, and anything else the disposal would have trouble breaking apart. Even smaller hard food items like popcorn kernels are problematic, causing damage to disposals and likely stopping up the drains.
  • Pasta and rice – Some foods we recommend against putting into the garbage disposal don’t cause damage to the unit itself, but we still feel we should warn you. Expandable foods like pasta and rice can stop up the drains since they absorb water and expand to stop the pipes.
  • Ice – It’s a common misconception that ice will sharpen the blades of your garbage disposal. As you’ve seen, these blades simply do not exist in your disposal, and it’s unnecessary to turn on the disposal to break down ice. (It will melt eventually, after all.)
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