What Not to Put in a Garbage Disposal

Young woman straining spaghetti over kitchen sink
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Invented in 1927 by John Hammes in Racine, Wisconin, the garbage disposal (usually marketed as a "food disposer)" was patented in 1935. Products from his InSinkErator company began selling them to the public in 1940, and almost from the beginning, there was controversy over their use. Many cities in the 1930s and 1940s began prohibiting garbage disposals because the flushing of food into sewer systems challenged the ability of waste-treatment facilities to handle the waste.

(Or so the cities argued.) Periodically, these bans have been enacted, then rescinded ever since then. Companies manufacturing the appliances have been quite successful at fighting such ordinances. 

Today, roughly 50% of all American home are equipped with garbage disposals, a much higher percentage than any other developed country. Canada, for example, has only 3% of homes with garbage disposals. 

Almost from the beginning, people have tried to use garbage disposals as a liquid garbage can to get rid of all manner of materials not suited for this method. Although most people now do know that the machine is for food items only, it might surprise you to know that there is quite a list of food items that should NOT be flushed down the drain through your garbage disposer: 

  • Rice and pasta. No matter how much water you run or how long you run the appliance, you can never break down rice or pasta small enough to effectively go down the drain. Both items swell when they are in contact with water, so the small pieces will eventually gather in the trap and swell until it clogs.
  • Animal bones. The garbage disposal is just not strong enough to break bones down into small enough pieces to fit through the drain.  Animal bones are the most common item that jams disposals.
  • Grease. The grease will eventually solidify and clog a portion, or all, of your drain.
  • Egg shells. Despite what you may have heard, egg shells do not sharpen disposal blades. Mostly they just end up clogging the line.
  • Stringy or tough-peeled vegetable. This includes asparagus, lettuce, celery and potato peels. Very small quantities might be handled, but do not try to flush large quantities through your garbage disposal, as you are inviting trouble. 

The old adage of “less is more” definitely applies to the garbage disposal. Only small amounts of table scraps should go into the disposal. If you find that something from the above list has jammed your disposal it’s a relatively easy process to unjam it.

The Case Against Installing a Garbage Disposal

If your house is serviced by a septic system, having a garbage disposal on your ktichen sink is a very bad idea. Food scraps flushed into a septic drain field will unbalance the chemistry of how waste breaks down in the septic tank under bacterial action. While some manufacturers claim to offer garbage disposals suitable for septic systems (they supposedly spray enzymes that help break down food), this is a questionable claim, at best. 

The best rule of thumb: septic system = NO garbage disposal. 

Even if you are serviced by municipal sewer service, you might want to think twice about installing a garbage disposal, and might even want to think about removing an existing one.

Despite protests by the appliance manufacturers, it's not easy for municipal sewer processing plants to handle huge quantities of food material flushed down drains. An increasing number of communities are now offering organic waste recycling programs with weekly pickup. And if you are a gardener, most non-animal food materials can be easily composted into a great plant food. 

More and more, environmentally conscious homeowners are choosing to remove their garbage disposals or let them sit idle.