A garbage disposal is not a trash can; you shouldn’t put every kitchen garbage in it. Like all machines, garbage disposals too have certain limitations. They are not designed for grinding everything, and everything they can grind need not be in your best interest.
Let me elaborate. You shouldn’t put certain food items in a garbage disposal, not because they cannot be ground, but because they can cause clogs in the drain pipes. That’s right; most problems occur after the food waste is ground and washed away from the garbage disposal.
Here are a few items you shouldn’t put in your garbage disposal;
PS: There are certain garbage disposal models that can grind some of these items but most can’t. Also, most garbage disposals can grind many of the items listed here, in small quantities.
Animal bones are really tough. Most garbage disposals, especially those with power ratings 3/4 HP and over, can easily grind soft bones like chicken and fish. But beef bones are another thing.
Websites like ConsumerReports grind beef bones to review the performances of garbage disposals, so given time, these can be ground. But for household usage, putting hard bones in your garbage disposal is a terrible idea.
Spaghetti, Rice, Noodles, Oats and anything similar
These food items are soft and squishy, so your garbage disposal blades (they use impellers, but never mind) can surely cut them, right? Yes, but the problem starts after the grinding. As you know, these food wastes when ground, becomes really paste-like and sticky. They can stick to the grinding components of the garbage disposal and cause clogs there. Even if you successfully wash them away from there, they will cause clogs in the drain pipes. This is true for bread loaves too. Just imagine unclogging the pipes from these sticky and rotting food wastes; do you really want to put them in the disposal?
Read more at: Unclogging rice/pasta in garbage disposal
Bread is soft and easily breakable, so many people think it is safe to put them in the garbage disposal.
You shouldn’t put bread in your garbage disposal as it will clog the disposal and the drain pipes. Bread has high amounts of Gluten, making it very sticky when ground with water, which can clog the disposal.
When ground, bread becomes a sticky paste and binds to the parts of the garbage disposal, including the tiny slots beneath its grinding components and the holes in its shredder ring, preventing any water and food wastes from draining. Therefore, even though bread looks harmless, it shouldn’t be put in the garbage disposal. Throw it in the trash can instead.
Coffee grounds look very innocent. In fact, I have heard people advising to use coffee grounds to clean garbage disposals. Trust me; you don’t want to do that. There are better ways to clean a garbage disposal.
What is the problem with coffee grounds? They are powdery and become paste-like when wet. Just remember what they look like when you take them out of the coffee machine. Not only are they sticky, but they are also very hard. They can get in the tiny spaces between the grinding components of your sink disposal, thus jamming them. They can also form a sludge in the disposal and the pipes giving rise to clogs. So coffee grounds are better of in a trash can than in a garbage disposal. They are also great for composting.
Further reading: Can you put coffee grounds in a garbage disposal?
When you consider putting a few handfuls of nuts into your garbage disposal, think of peanut butter. While tasty (I love it!), think how hard it is to spread the peanut butter on a slice of bread; it takes some real hard work to get it off the knife. That is what is going to happen to your garbage disposal. Whether Almond, Hazelnut, or Pistachio, nuts become a sticky paste when ground, particularly when they are wet. They will stick to the internal parts of your garbage disposal, refusing to be washed away, leading to clogs and smells.
It is better to leave this type of food waste in the bin. It is alright to grind a few of them with enough water to wash them away.
Seafood shells are a big no for a garbage disposal. Shells of crabs, lobsters, etc., are hard, and they will just jump around inside the sink disposal if you try to grind them. Even if your garbage disposal manages to grind them, they can cause clogs in the pipelines. So avoid these at all costs.
Fruit pits and seeds
Fruit seeds and pits are hard. Fruit pits cannot be cut with a knife. So don’t expect your garbage disposal to grind them with ease. Fruit seeds, even though they are tiny, are really hard to wash away. They can also get into the teeny spaces between the grinding components of your garbage disposal, thus blocking its free movement.
What is my garbage disposal good for if I can’t even put onion skins in it? Many have asked this question, including me. But the truth is, garbage disposals can’t grind onion peels. These thin peels often manage to escape the disposal blades since they are thin, and then they start clogging the pipes. This problem happens only with the dry, outer layer of the onions and the thin membrane just beneath it. It is alright to grind chopped or full onions without this skin.
Many people are surprised when plumbers say their drams are clogged with eggshells. They will say; it worked alright last time and the time before! You will have a hard time believing that eggshells can cause your pipes to clog even though you ground them in your garbage disposal.
The real villain here is not the eggshell itself; it is the think membrane you see just beneath the shell. Just like onion skins, these thin membranes get into the pipes without getting ground, and they start catching everything that passes through. This eventually leads to a nasty clog.
Sometimes these thin membranes can get wrapped around the free-swinging impellers of your garbage disposal and prevent their free movement. This will make the disposer less efficient leading to many other problems.
There is no problem with grinding an eggshell once in a while, but don’t ever think of cramming your disposer with them.
Further reading: Can you put eggshells in a garbage disposal?
Fats, oils and greases
It can be tempting to pour all that grease from your last cooking into the kitchen sink. Whether you have a garbage disposal or not, pouring fats, oils, or greases into your drain pipes is not a good idea. If you do, they will solidify in the pipes, and in the garbage disposal, catching all the food wastes that come through, eventually leading to clogs.
That being said, every dish you prepare will have some oil or fat in it, but that is ok. This is why plumbers recommend running cold water instead of hot water when using garbage disposals. Hot water will dilute these fats, and they will solidify later somewhere down the drain. Otherwise, they are ground and disposed of along with the food wastes.
Putting potato peels in your garbage disposal is like putting mashed potatoes in there. Both become slimy when ground with water. And since they are thin, some of them escape into the drain pipes without getting ground. In both cases, they will eventually lead to clogs and headaches. To my advice is, leave the potato peels in the bin.
Fibrous fruits and vegetables
Fibrous fruits and vegetables like celery, corn husks, and pumpkins are another on the list of many things you shouldn’t put in a garbage disposal. Your garbage disposal can easily grind them for sure. But the problem is; the long fibers in them are cut into small pieces but not small enough to avoid clogs. These fibers accumulate in the pipes just like hair, and they create a net that traps all the food wastes leading to multiple clogs.
There are many ways to dispose of paint but putting it in your garbage disposal is definitely NOT one of those. Paints become hard after some time. So if you pour it down the sink, it will sit in the garbage disposals and the pipes and then solidify and cause clogs that are really hard to remove. It is almost impossible to remove hardened paint from inside a garbage disposal. So pouring paint into your disposer will be a costly mistake.
Broken glass or metal
Glass and metal are not food waste, and so they have no business in a garbage disposal. However, I have heard many ‘experts’ advising their friends to use broken glass to sharpen garbage disposal blades. Here is a good, practical guide if you don’t know how to ‘sharpen’ your garbage disposal’s blades.
You shouldn’t put any non-food wastes into your garbage disposal, including glass and metal. If you put glass into your garbage disposal, there is a good chance a shard can come flying out of the sink; you really don’t want that. Also, ground glass can block the impeller blades from moving, leading to many other problems.
If something metal falls into your garbage disposal, you will know instantly; you will hear a loud, clanking sound.
If glass or metal falls into your disposer, you should stop it immediately and remove them with a pair of tongs. Make sure that you get all of it out before rerunning the disposer.
Further reading: How to get broken glass out of garbage disposal?.
When you remove a turkey or a chicken’s skin, put that in the trash can, NOT in your garbage disposal. As you know, poultry skins are rubbery and filled with lots of fat. They are hard to grind, and grinding them will lead to smelly clogs. So it is advised to avoid doing this.
Apples, oranges, bananas, etc. come with some tiny stickers on them. They are food-grade stickers and are edible. But I bet your garbage disposal does not know that! The glue on the stickers can stick to your garbage disposal’s grinding components, making it less grinding overtime or leading to other problems. The same can stick inside your pipes too, making clogs.
It can be really tempting to put pet food remains into your garbage disposal. Whether you are religious or not, resist this particular temptation for the sake of your money. Pet food, when ground, gets really sticky, and you don’t want them sticking in your garbage disposal and drain pipes. Please put them in the trash can instead.