What Not to Put in a Garbage Disposal: The Real List
The answer depends partly on your disposal. Grease is a hard no for everyone; for bones and fibrous scraps, it comes down to the model.
The one thing never to put in a garbage disposal is fat, oil or grease: every major manufacturer says so, because it coats and hardens in pipes. Beyond that, keep out non-food items, large bones, fibrous scraps like corn husks and onion skins, and avoid pouring in big batches of coffee grounds, pasta or rice at once. What your disposal can handle depends on its model, so check the manual. Always run cold water while grinding, and never reach into the chamber.
The never list
| Item | Why |
|---|---|
| Fats, oils and grease (bacon fat, frying oil, butter, meat drippings) | Liquid when hot, solid when cool; builds up in pipes and sewer lines |
| Non-food items (twist ties, bottle caps, foil, plastic, rubber bands, glass) | Jam the turntable or damage parts |
| Paper towels, napkins, wipes | Do not break down; clog the trap |
| Chemical drain cleaners | Can damage seals and parts; hazardous during later repairs |
| Paint, solvents, cigarette butts | Not food waste; environmental hazard |
| Your hand, utensils used to push food in | Use tongs and let cold water carry food in |
Grease is also the top item on public guidance for drains in general. The US EPA’s septic care page says never to pour cooking oil or grease down the drain, and lists other fats such as butter and heavy cream too. Let grease cool in a can or jar and throw it away, or follow your local collection rules.
Depends on your model
Manufacturers rate their disposals differently. InSinkErator’s published “what can I grind” list is a good example: its standard series is listed for everyday soft scraps (fruit, bread, pasta, rice, potato peels, coffee grounds, eggshells), its mid-tier series adds tougher items like avocado and peach pits and raw meat, and only its top-tier series lists chicken bones, corn cobs, celery and banana peels. Other brands publish similar guidance in their manuals. If your manual does not list an item, treat it as a no.
Bones
Small, soft bones may be fine in a high-powered model rated for them. Large beef or pork bones are too hard for household units and will usually just rattle around or jam the plate. In a basic model, keep all bones out.
Fibrous and stringy vegetables
Corn husks, celery strings, artichoke leaves, rhubarb and asparagus ends can wrap around parts or pass through as long fibers that tangle in the trap. Onion and garlic skins behave similarly. See can you put onions in a garbage disposal for why thin skins are a problem.
Pasta, rice and bread
Manufacturers do list these as grindable. The issue is quantity: starches swell with water and can form a paste in the trap. A spoonful of leftover rice is fine. A whole pot of overcooked pasta is not. Scrape most of it into the trash and grind only small amounts with plenty of cold water.
Coffee grounds
InSinkErator says coffee grounds do not harm the disposal itself, but warns that because they are sedimentary they can cause clogs or slow drains if too much goes in at once, especially with older or restricted plumbing. Small amounts with a strong cold-water flush are fine; a full filter basket every day is better composted.
Eggshells: the myth
You will often read that eggshells “sharpen the blades.” Household disposals do not have sharp blades, so there is nothing to sharpen. The same manufacturer guidance treats eggshells like coffee grounds: not harmful to the unit, but gritty material that can build up in pipes if you send a lot at once. A few shells are fine. A dozen at a time is asking for a slow drain.
Fruit pits and hard seeds
Peach and avocado pits are rated only for more powerful units. In a basic model they can jam the turntable. When in doubt, throw them out.
What goes down easily
- Small soft food scraps from plates
- Most cooked vegetables and fruit pieces
- Small amounts of soft leftovers
- Citrus rinds in small pieces (listed as grindable by at least one major maker)
- Ice cubes, which help scour the chamber
How to grind properly
- Turn on a moderate stream of cold water first.
- Switch on the disposal.
- Feed food in gradually. Manufacturers advise against pre-loading the chamber before switching on.
- When the grinding sound evens out, turn off the disposal but keep the water running for a few more seconds.
If you do get a jam, see garbage disposal not spinning. If you are choosing a new unit and want it to handle tougher scraps, our horsepower guide explains what the specs mean.
If you are on a septic system
The EPA advises limiting disposal use on septic systems because food waste adds solids to the tank, so it needs pumping more often. Composting more scraps and grinding less is the simplest way to reduce that load.
When to call a pro
Call a plumber if water backs up into both sides of a double sink or into the dishwasher, if the drain stays slow after you clear the trap, or if you suspect a grease blockage further down the line. Repeated jams in a disposal that is only used for soft scraps may mean the unit is wearing out.
Bottom line
Keep grease and non-food items out always. Go easy on starches, coffee grounds and eggshells. Keep bones, pits and fibrous scraps out unless your manual says your model can handle them. Cold water and small batches prevent most problems.
FAQ
Can I put grease down the disposal if I run hot water?
No. Hot water only moves the grease further down the line, where it cools and hardens.
Do eggshells really sharpen disposal blades?
No. Household disposals use blunt lugs and a grind ring, not blades. Eggshells add grit to the drain.
Are banana peels OK?
Some high-end models are rated for them; many basic models are not. They are fibrous, so compost them if your manual does not list them.
Can I put dish soap down the disposal?
Yes. A soapy water flush is a normal way to clean the chamber and does no harm.
