Dull Garbage Disposal Blades: How to Fix

    Knifes in a circle

    Over time, a garbage disposal's blades become dull and unable to grind food as efficiently as they used to. After years of service, you'll probably notice that it takes longer to grind your food waste. Simply put, your disposal just isn't working as it once was. 

    When a garbage disposal is no longer efficient at grinding food waste, it's time to take action to correct the problem. Larger pieces of waste could slip thru and cause a clog, either in your disposal or your plumbing. This article will help you "sharpen" your garbage disposal's blades and show you how to prevent future problems.

    How to Fix Dull Garbage Disposal Blades


    Before we look at how to sharpen blades, let's first take a look at how a garbage disposal actually works.

    How a Garbage Disposal Works

    Garbage disposals work differently than most people think. With all the talk of "blades" we often assume that there are 2 or 3 knife-like blades swirling inside the grinding chamber, pulverizing anything that dares to enter. But in actuality, that just isn't the case.

    What we assume are "knifes" are actually 2 blunt impellers that are securely mounted on a plate that rapidly spins around. The centrical force created, pushes the food waste to the sides of the grind chamber.

    As the food slams into the sides of the disposal, there's a stationary grind ring with metal teeth waiting to tear into the waste, breaking it up so the cold stream of water can flush it down your drain.

    This video shows how a garbage disposal operates:

    As you can see, the grind ring is covered with sharp, teeth-like shredders, which is why it's sometimes called the shredder ring. Over time, the shredders can become dull or become encased in food build-up, making them less effective at breaking down food waste.

    How to Sharpen Garbage Disposal Blades

    Since a garbage disposal doesn't have blades, you won't be able to sharpen them. But can you sharpen the grind ring?

    Actually, you cannot . . . at least, not technically. 

    But you can clean the grind ring, which will give the illusion that you did sharpen the teeth, since the disposal will run more efficiently. So cleaning is an important step to keeping your disposal running in top form. 

    When gunk builds-up in the crevices of the teeth, the grind ring will seem duller than it actually is. Over time, you many even begin to notice that your garbage disposal develops an unpleasant odor as the food and gunk begins to rot inside.

    This article will give you step-by-step directions on how to resolve an odor problem.

    Method 1: Ice Cubes and Salt

    The most popular method to clean a grind ring is to throw a handful of salt and 8 to 10 ice cubes into the disposal while running cold water.

    Allow the garbage disposal to run for about a minute before turning it OFF. Then, continue to flush with cold water for another 15 seconds. This will allow any remaining debris to exit your disposal and go down the drain.

    The ice breaks into thousands of tiny pieces and, along with the salt, scrubs the inside of your grind chamber. Toss a wedged lemon in when you're finished, to give a fresh citrus smell.

    Method 2: Hot Soapy Water

    If you don't have ice cubes available, or you just want to try something different, this method is very effective.

    First, insert the drain stopper and fill the sink about half full of hot, soapy water. Then, remove the drain stopper. As the water goes down the drain it will be forced into the garbage disposal. 

    Before the sink is empty, turn ON the disposal, as well as the cold water tap. Allow both to run for 2 to 3 minutes. Turn the disposal OFF and leave the cold water tap running for another 15 seconds.

    How to Prevent Dull Blades

    Prevention is always better than repairing a problem, not to mention it's also less expensive.

    There's a certain amount of wear-n-tear that you won't be able to stop, but there are things that you can do (or not do) to keep your grind ring from getting dull. Read our full article on how to keep your garbage disposal healthy​. 

    Grease and Fats

    You should never put grease or fats into your garbage disposal. Besides clogging your pipes and creating a major plumbing problem, they also tend to build-up inside your garbage disposal. 

    Over time, the problem can become so bad that the grind ring is nearly useless, and even trying to clean it may be ineffective.

    Fibrous Foods

    Fibrous foods can also be a problem. Since they tend to take longer to grind, large pieces are often left in the disposal. In fact, sometimes these foods simply aren't able to be totally ground. This can cause  your garbage disposal to develop a bad odor or even clog. 

    The left over debris can get tangled in the grind ring, making it difficult to grind other waste. The foods listed below should be thrown in the trash or composted, but never put in your garbage disposal:

    • Potato Skins
    • Banana Peels
    • Lettuce
    • Celery
    • Corn Husks

    Do You Think It's Time For A New Garbage Disposal?