A good dishwasher gets a lot of attention as lifesavers in the kitchen, but the humble garbage disposal is another true workhorse that can help make clean-up a breeze. If you’re lucky enough to have the appliance installed in your kitchen sink, you know that it can take care of food scraps in a flash, leaving your garbage less stinky, plus help prevent backed-up sinks that are just plain gross to deal with.

But as effective as they are, garbage disposals can also be finicky machines, prone to breakage and less-than-pleasant backups when you put the wrong things inside. Not to mention, they can be costly to repair.

To help ensure your machine runs at peak performance for many years to come, we tapped the experts in the Good Housekeeping Institute‘s Cleaning Lab for some pointers on what items should never make their way into your garbage disposal. Instead, you can throw these food bits in your regular garbage, or opt for composting them.  Also, if you need to clean your garbage disposal, here’s some advice!

1. Bones

This one may seem obvious, but big bones from chicken carcasses, ribs and other animal proteins shouldn’t make their way into your disposal. They’ll simply spin around, possibly even damaging the blades. And while some may say small bones from food like fish can go down the disposal, we caution against it and suggest taking these items to the trash instead.

2. Shells

Similarly, you should never put oyster or clamshells down the disposal — they’re much too hard for the blades to tackle. The hard exoskeletons of other shellfish, including crabs, lobster and shrimp, are also better off in the garbage can, as they can cause damage to both your system’s blades and pipes.

3. Coffee grounds

You may have heard conflicting advice on coffee grounds — there’s a common misconception that they can help clean your disposal. And while they do seem innocent enough, our experts say they can actually pile up in the system, leading to a sludgy mess that could potentially clog your pipes.

4. Eggshells

Eggshells are another item that gets tossed around as a good way to clean your machine or even sharpen the blades, but we advise against this as well. The membrane lining inside the shell can also build up, leading to trouble.

5. Fibrous vegetables

Garbage disposals make quick work of discarding veggie scraps, but foods like celery, asparagus and corn husks should never make it into your disposal. The long, fine strands that compose these items can get tangled up in the blades, wreaking havoc on the machine’s efficiency.

6. Produce stickers

You know those little stickers that detail the food’s PLU code for reference at the grocery store? Make sure to peel those off and toss them in the trash before discarding any food scraps in the garbage disposal. They can attract other bits of debris that could eventually causing a blockage.

7. Pits

The pits from fruit like peaches, plums, mangos and avocado should never make their way down your drain. Like bones, they’re much too tough for the blades and can cause damage. They may also get lodged in pipes if they happen to make their way through.

8. Pasta and rice

Kids left some macaroni, a hunk of lasagna or remnants of fried rice on their plate? Scrape that right into the trash before rinsing the dish — starchy foods like pasta and rice expand when exposed to liquid, even after they’ve been fully cooked. This can cause buildup in your disposal, eventually leading to plumbing problems.

9. Potato peels

Similarly, the starch from potato peels can swell and get gummy in your garbage disposal, causing issues down the line.

vegetable scraps in kitchen sink with garbage disposal, above view

Liudmila Chernetska//Getty Images

10. Oats

Don’t dump the last bits of your morning oatmeal into the disposal, either. Like other starchy foods, this seemingly innocent item expands and can create a sticky mess inside the appliance.

11. Beans

Chickpeas, white beans, black beans… whatever legume you enjoy, they should end up in the trash rather than the disposal. Like starches, these items have a tendency to get sticky inside the machine and may even coat the blades, leading to efficiency issues and even full malfunction.

12. Onion skins

Similar to eggs, the thin membrane on the inside of an onion’s skin can get lodged in the drain, which can trap other food that would otherwise make it down the pipes and cause clogs. Onions and their skins also tend to be stringy and can wrap around the blades.

13. Nuts

Nuts are not only hard and can eventually dull your garbage disposal’s blades, but they can also create a muddy mess inside that can eventually lead to blockages. Think about it: Nut butters, like peanut and almond butter, are made by grinding the nuts into a paste!

14. Grease, oil and other fats

Grease, oil and other fats like melted butter should never go down your sink — regardless of whether you have a disposal. It’s the same concept as what fat can do to your arteries. When it hardens, it can cause stubborn clogs in your drain and pipes.

Brigitt Earley

Contributing Writer

Brigitt is a writer, editor and craft stylist with nearly 15 years of experience. She specializes in lifestyle topics, including home, health, parenting, beauty, style, food, entertaining, travel and weddings. She has written for Glamour, People, Good Housekeeping, Women’s Health, Real Simple, Martha Stewart, Apartment Therapy, The Spruce, and more.