What Not to Put in a Garbage Disposal — 15 Items to Avoid
Garbage disposals can handle most soft food scraps, but certain items will jam the flywheel, clog the drain, or wear out the motor years ahead of schedule. We have seen the same handful of foods cause problems over and over. This is the full list, based on manufacturer guidelines and what plumbers and homeowners report most frequently.
If you are already dealing with a jam or clog from something on this list, skip ahead to signs you put the wrong thing in. For routine upkeep, see our garbage disposal maintenance guide.
The quick list — 15 things that damage your disposal
Here is the complete list. Details on why each one causes problems follow below.
Fats and Oils
- Grease and cooking oil — solidifies in pipes, creates blockages
- Butter and lard — same problem as liquid grease, just slower to build up
- Salad dressing — oil-based dressings coat the drain line
Fibrous Foods 4. Celery — long fibers wrap around the flywheel 5. Asparagus — same fiber wrapping problem as celery 6. Artichoke leaves — tough, stringy, and almost impossible to grind 7. Corn husks and silk — fibers tangle around the impellers
Starchy Foods 8. Potato peels — form a thick paste that coats the chamber and clogs the drain 9. Pasta — expands with water even after grinding 10. Rice — same expansion problem as pasta, packs into sludge
Problem Solids 11. Coffee grounds — accumulate in the P-trap as dense sludge over weeks 12. Egg shells — the inner membrane wraps around grinding components 13. Large bones (beef, pork ribs) — can damage impellers and jam the motor 14. Fruit pits and seeds — too hard to grind, bounce around and jam
Never 15. Non-food items — glass, metal, plastic, rubber bands, twist ties. Obvious, but it happens more often than you would think, especially with small items that fall in while washing dishes.
Why Each Item Causes Problems
Grease, oil, and fat
Grease is the single worst thing for a garbage disposal and the plumbing downstream. It goes down as a liquid but solidifies as it cools in the drain line, narrowing the pipe over time until water backs up.
Here is the part most people get wrong: hot water makes it worse, not better. Running hot water while grinding melts grease into a thin liquid that flows deep into the drain line before solidifying. Cold water is correct — it keeps grease solid so the disposal can break it into small chunks that flush through without coating the pipes.
Pour cooking grease into a container and throw it in the trash. Old jars, tin cans, even a folded piece of foil work. Anything except the drain.
Fibrous vegetables
Celery, asparagus, artichokes, and corn husks all have the same problem: long, stringy fibers. A disposal spins at 1,725 RPM (InSinkErator induction motors) or up to 2,800 RPM (Waste King permanent magnet motors), and those fibers wrap around the flywheel and impellers like thread on a spool. The motor keeps spinning but cannot grind anything. You hear humming, then the overload trips.
Toss fibrous vegetable scraps in the trash or a compost bin. If you accidentally grind some and the disposal starts humming, see our guide on how to unjam a garbage disposal.
Starchy foods
Potato peels, pasta, and rice all expand when they absorb water. Potato peels are the worst — they form a starchy paste that coats the grinding chamber walls and clogs the drain opening. We have pulled apart P-traps that were packed solid with a paste of potato starch and water.
Pasta and rice do the same thing on a smaller scale. A few noodles are not going to destroy anything, but grinding a full serving of leftover pasta creates an expanding mass in the drain line. Best to scrape plates into the trash before rinsing.
Coffee grounds
Coffee grounds seem harmless. They are small, soft, and flush through the disposal without a sound. The problem is what happens in the P-trap. Grounds settle and compact into dense, wet sludge that builds up over weeks. Eventually the drain slows down, and you are looking at a $70 to $200 repair bill for a clog that started with something that seemed completely fine.
If you make coffee daily, either compost the grounds or throw them in the trash. Composting at home is a better use for coffee grounds anyway — they are good for soil.
Bones and hard items
Small chicken wing bones are actually fine. They break apart quickly and the fragments help scrub the grinding chamber, similar to the ice cube cleaning method. This surprises people, but InSinkErator’s own usage guidelines confirm that small poultry bones are safe.
Large bones are a different story. Beef bones, pork rib bones, and anything thicker than a chicken wing can damage the impellers or stall the motor. Fruit pits (peach, avocado, cherry) and hard seeds are the same story — too dense to grind. They just bounce around the chamber until something jams.
Egg shells
This one generates debate. The shells themselves grind into harmless grit. The problem is the thin membrane lining the inside of the shell. It wraps around the grinding components and impellers, and over time that buildup traps food particles. One or two eggs will not cause a noticeable issue, but regularly grinding shells builds up membrane residue that traps food particles.
Manufacturers generally advise against putting egg shells in a disposal. We agree — composting or trashing egg shells costs nothing and avoids a slow-building problem.
What You CAN Safely Put in a Disposal
Not everything is off limits. Disposals handle these foods without issue:
- Soft fruit — banana chunks, melon, berries, citrus segments
- Cooked vegetables — soft, non-fibrous leftovers (broccoli florets, green beans, squash)
- Small chicken bones — break apart quickly, actually help clean the chamber
- Citrus peels — lemon, lime, and orange peels freshen the unit and scrub lightly
- Ice cubes — scrub the grinding components; we recommend a handful weekly for maintenance
- Bread and crackers — break down immediately with water
- Cooked meat scraps — small amounts, not large chunks
The general rule: if it is soft enough to break apart with a fork, the disposal can handle it. Always run cold water before, during, and for 15 seconds after grinding. Feed food in gradually — do not cram a full plate of scraps in at once.
For a full cleaning routine, see how to clean your garbage disposal.
Signs you put the wrong thing in
Already made a mistake? Here is what each symptom means and where to find the fix.
| Symptom | Likely Cause | What to Do |
|---|---|---|
| Disposal hums but will not spin | Something jammed the flywheel | Unjam a garbage disposal |
| Slow draining or standing water | Clog in P-trap or drain line | Unclog a garbage disposal |
| Bad smell that will not go away | Food trapped under splash guard | Fix garbage disposal odor |
| Disposal will not turn on | Overload tripped or motor burned out | Check the reset button on the bottom of the unit |
The 1/4-inch Allen wrench hole on the bottom of the disposal is your best friend for jams. Insert the wrench and turn it back and forth to free the flywheel. Most disposals ship with a wrench taped to the unit — check before buying one.
A disposal lifespan of 10-12 years is typical. Regular abuse (grinding the wrong foods, skipping maintenance) can cut that to 5-7 years, while good habits push quality units past 15.
FAQ
Can you put egg shells in a garbage disposal?
We recommend against it. The shells grind into harmless grit, but the thin membrane inside the shell wraps around grinding components and traps food particles. One or two eggs will not cause a problem, but regular shell grinding builds up residue that reduces performance and can contribute to odor. Compost or trash egg shells instead.
Can you put coffee grounds in a garbage disposal?
No. Coffee grounds are one of the most common causes of disposal drain clogs. They pass through the grinding chamber without issue, but they settle and compact in the P-trap over weeks, forming dense sludge. If you grind coffee daily, expect to deal with slow draining within a few months. Compost the grounds or throw them in the trash.
Can you put bones in a garbage disposal?
Small poultry bones (chicken wings, drumstick tips) are safe and actually help clean the grinding chamber. Large bones — beef, pork ribs, lamb — can damage impellers or stall the motor. InSinkErator’s 1/2 HP Badger series can handle small chicken bones without issue. Heavier bones need the trash can.
Can you put rice or pasta in a garbage disposal?
Small amounts will not cause immediate damage, but rice and pasta continue to expand as they absorb water in the drain line. A full serving of leftover spaghetti or a cup of rice can swell enough to restrict the drain pipe. Scrape plates into the trash before rinsing, and if you do accidentally grind a small amount, flush with cold water for at least 30 seconds.