What not to put down your disposal – according to a licensed plumber


I want to start off by clearly stating this list may not match what the manufacturer of your disposal says is safe to put down your disposal.  For example;  Insinkerator brand disposals state that you can put “uneaten fast food” down your disposal  (seriously, that they had to put uneaten on there scares me) we are going to advise against the urge of putting uneaten fast food down your disposal and we’re going to let you know why certain foods like fast food are a no-no in our professional opinion and experience.


Not all disposals are created equal


Disposals come with several different options including horsepower and single grind vs double or even triple grind.  Not all disposals are created equal, so you can’t assume that the 1/3 horsepower special from the hardware store will hold up the same as the 1½ horsepower triple grind version.  We want to guide you through being proactive with your disposal and to use it safely no matter how many horsepower it may have or how many grind levels it may possess.


Your disposal isn’t the only thing to consider when deciding what to put down the drain


Your disposal, even if 1/3 horsepower can handle a lot of food debris but what isn’t always considered is the condition of your drain line after your disposal.  Most kitchen stoppages occur beyond the disposal in the disposal tee or p-trap and sometimes even the drain section in the wall.  Your kitchen sink line is 1½” diameter pipe, that is small when you think about it, it is about the diameter of a large barrel curling iron.  (I know, chick reference, but I am a chick) We expect a lot of that small pipe when we’re putting things down the disposal and what is often the cause of stoppages is a kitchen sink line that has been reduced in diameter due to buildup of food and grease in the line, taking that 1½ diameter down to less than half of its original diameter.  Now we’re working with a line that is like at ¾” diameter on the inside, coated with sticky debris and asking it to handle what we throw down the disposal, and this is where bad things happen. There are even some fittings that are restrictive by design!


How to use your disposal


This may seem redundant and simple, but have you ever learned the proper steps for using your disposal?

  1. Always use your disposal while the cold water is running the entire time.
  2. Turn the disposal on. You will want to make sure that your disposal is running before you put food waste down.
  3. Cramming food down your disposal can cause the disposal to jam, best practices when putting food scraps down your disposal is to send them down in small portions.
  4. Once the food waste has been processed, turn the disposal off while allowing the cold water to run for a few more seconds to ensure that all of the debris has been properly flushed from the disposal and the water is able to carry the food waste past the disposal tee and through the p-trap under your kitchen sink.


What not to put down your disposal to prevent stoppages in your drain line


The following list is a guideline of foods not to put down your disposal, not necessarily because they are bad for your disposal but because they have been in our experience the foods that most commonly cause stoppages in kitchen sinks.


  1. Coffee grounds – Coffee grounds are sedimentary in nature and can quickly buildup in your kitchen drain line causing a stoppage. A great use for coffee grounds is in gardens, if you’re not a gardener yourself, I bet you know someone that is or there are several gardening Facebook groups where people would love to use your coffee grounds for their gardens and composts.
  2. Egg shells – There is a common myth that eggshells are great to put down your disposal because the edges of the eggshells will sharpen the blades inside your disposal. This isn’t true.  Your disposal doesn’t have any blades and eggshells, like coffee grounds are sedimentary and will build up in your drain line creating a stoppage.  Eggshells are also great for composts in gardens so if you can recycle them, otherwise eggshells are best sent to your trashcan rather than your garbage disposal.
  3. Pasta – Whether the pasta is wet or dry you will want to avoid sending it down your disposal. Pasta can continue to absorb water in your drain line and continue to expand inside your line creating a stoppage.
  4. Rice – Just like pasta rice will continue to absorb water while sitting in your drain line and expand in your drain line. Rice is better thrown away that sent down your drain system.
  5. Beans – You’re probably catching on, foods that expand with water shouldn’t be sent down your drain system, they should be sent safely to your trashcan. Even worse, if these soft, water absorbing foods aren’t sent down your line with enough water they can sit in your line and harden again – creating a concrete like stoppage in your line.  Do your family a favor and throw pasta, rice and beans away rather than down your sink.
  6. Fibrous vegetables like celery – Fibrous, stringy vegetables are often the culprit of kitchen sink stoppages, this seems especially true on Thanksgiving. This is often because too much of the product is being sent down the disposal at once for the disposal to break to properly break down all of the stringy bits.  These stringy bits can also catch on the teeth inside of your disposal and create an awful smell at your sink.
  7. Grease or greasy foods, like uneaten fast food (I couldn’t resist) grease should never go down your kitchen line, ever. Grease is one of the leading causes of kitchen stoppages and even in small amounts can buildup on the inside of your pipe reducing the inside diameter drastically and creating a sticky surface for everything to stick too.