15 Things Never to Put in a Garbage Disposal

Most garbage disposal problems are not caused by a bad unit. They are caused by the wrong things going down the drain. Knowing what not to put in garbage disposal units is the single most useful thing a homeowner can learn about their kitchen sink, because one bad habit can jam the motor, clog the drain, or shorten the life of a disposal by years. This guide covers 15 specific items to keep out of your disposal, explains exactly why each one causes trouble, and tells you what to do with it instead. If you are unsure whether your disposal is the right size for your household, our garbage disposal horsepower guide will help, and the garbage disposals hub has more maintenance guides.

Fats, Oils, and Grease

1. Cooking grease and oil. Grease is the number one enemy of drains. It goes down as a liquid, then cools and hardens inside your pipes, coating the walls and catching other debris until the drain narrows and clogs. A disposal does nothing to prevent this, because the grease passes through the grind chamber unchanged and solidifies downstream. Pour cooled grease into a sealed container and throw it in the trash, or save bacon fat in a jar for cooking. 2. Butter and melted fat from meat. The same rule applies. Skim fat from pans and roasting trays into the trash, not the sink, even if you run hot water. Hot water only moves the problem further down the pipe before it hardens. 3. Salad dressing and oily sauces in large amounts. A thin residue rinsed from a plate is fine, but pouring out a jar of dressing or a pan of oily sauce belongs in the trash. These liquids add a grease coating to your drains with every pour, and the buildup is cumulative and expensive to clear.

Fibrous Vegetables That Wrap the Mechanism

4. Celery. Celery strings are long, tough fibers that do not grind cleanly. Instead, they wrap around the disposal turntable and grind ring, slowing the motor and eventually causing a jam that requires manual clearing. Chop celery for the trash or compost it instead. 5. Asparagus and artichoke leaves. These have the same stringy fiber problem as celery, and artichoke leaves are especially tough. Neither belongs in a disposal in any amount. 6. Corn husks and onion skins. Corn husks are fibrous sheets that wrap and tangle, while onion skins are thin, papery layers that slip past the grind ring unground and catch in the drain trap, where they build up into clogs. Both belong in the trash or compost. 7. Banana peels and other tough peels. Banana peels are thick and fibrous, and they grind poorly. Compost them instead, where they break down happily. The same goes for large amounts of any tough peel.

Starchy Foods That Swell and Clog

8. Potato peels. Potato peels are the classic disposal clog. They grind into a starchy paste that swells with water and forms a thick, glue-like blockage in the drain trap. Even small amounts add up, and a large pile from peeling a bag of potatoes will almost guarantee a clog. Throw peels in the trash or compost. 9. Pasta and rice. Pasta and rice absorb water and expand long after they go down the drain. A cup of cooked pasta can swell to fill a section of pipe, and because it is soft, it does not grind into particles that wash away cleanly. Scrape leftover pasta and rice into the trash. 10. Bread, dough, and flour. Bread turns to paste in water, and raw dough expands as it absorbs moisture. Flour poured down the drain mixes with water into a thick slurry that hardens into a blockage. All of these belong in the trash, never in the disposal.

Hard Items That Damage the Grind Ring

11. Bones larger than small fish or chicken bones. Small, soft bones from fish and chicken are fine in a mid-size or larger disposal, but beef bones, pork bones, and large poultry bones are too hard. They dull the grind ring, can crack the chamber, and will stall the motor. Put large bones in the trash. If you are choosing a new unit, our batch feed vs continuous feed guide explains how feed type interacts with grinding performance. 12. Fruit pits, seeds, and shells. Peach pits, avocado pits, and nut shells are hard enough to damage the grind mechanism, and small seeds slip through unground and collect in the trap. Nutshells in particular are dense and abrasive. Trash them all. 13. Glass, metal, and plastic. A spoon, bottle cap, twist tie, or piece of broken glass that falls into the disposal can chip the grind ring, break the splash guard, or jam the turntable instantly. If anything non-food falls in, turn the unit off at the switch, never reach in with your hand, and retrieve it with tongs or pliers.

Coffee Grounds, Eggshells, and Common Myths

14. Coffee grounds. Coffee grounds are one of the most common disposal mistakes because they seem harmless. In reality, grounds clump together in water into a dense, sludgy sediment that settles in the drain trap and builds into a stubborn clog, especially in homes with older or slow-draining pipes. They also do nothing to sharpen the mechanism, despite the old myth. Compost coffee grounds instead, where they are genuinely useful for the garden. 15. Eggshells in large amounts. The old advice that eggshells sharpen disposal blades is a myth, because disposals do not have blades. Small amounts of shell are harmless, but the thin membrane inside the shell peels off and wraps around the mechanism, and large amounts of shell grit settle in the trap. Compost eggshells or throw them in the trash. A related myth is that ice cubes clean a disposal. Ice can help dislodge loose debris, and it is safe in moderation, but it does not sharpen anything and should not be used as a substitute for real cleaning. For actual odor removal, see our guide on how to fix a smelly garbage disposal, which covers the cleaning steps that actually work.

Non-Food Items and Chemicals

Beyond the 15 items above, there is a whole category of things that should never go near a disposal under any circumstances. Paper towels, napkins, and tissues absorb water, swell, and clog drains, and they do not grind into particles that wash away. Cigarette butts, cotton balls, and bandages belong in the trash. Medications should never go down the drain, because they pass through wastewater treatment into waterways; use a drug take-back program instead. Harsh chemicals, drain cleaners, bleach, and paint are also off limits. Chemical drain cleaners can splash back during grinding, damage the rubber seals and splash guard, and corrode the chamber, while paint hardens inside pipes. If your drain is slow, the fix is a plunger or a plumber, not a bottle of chemicals poured into a disposal. Feminine hygiene products, wipes labeled flushable, and diapers are designed not to break down in water, and they will jam a disposal and clog a sewer line. The rule is simple: if it is not a small amount of soft food, it does not belong in the disposal.

What to Do Instead and When to Call a Plumber

The simplest system is a small trash bowl on the counter while you cook, so peels, grease containers, and scraps go straight to the trash or compost instead of the sink. Keep a sealed jar for used cooking oil, and take it to a recycling drop-off or throw it in the trash once full. Compost vegetable scraps, coffee grounds, and eggshells if you have a pile or curbside organics bin. For a comparison of the two approaches, read our guide on garbage disposal vs composting. If your disposal is already jammed, turn it off, press the reset button on the bottom of the unit after clearing the cause with tongs, and try again with cold water running. If the unit hums but does not spin, leaks from the bottom seal, trips the breaker, or the drain stays slow after clearing the disposal, stop and call a plumber, because the problem may be in the drain line rather than the unit. A disposal that is used correctly, fed gradually with cold water, and kept free of the items on this list will run quietly for 8 to 12 years. The items on this list are responsible for most of the rest, so keeping them out is the cheapest maintenance you will ever do.