It might seem like your garbage disposal can grind up just about anything, but tossing the wrong items down the drain is a sure way to end up with foul odors, stubborn clogs, or even a broken appliance. While soft foods, ice cubes, chopped items, and fruit peels are generally safe for the disposal, some things belong in the trash or compost pile instead. I spoke with master plumbers Roy Barnes and Hendrik Vandepoll, co-owners of Service Force Plumbing in Rockville, Maryland, to get their expert tips on keeping your garbage disposal in top shape.
1. Fat, Grease, and Oil
While your garbage disposal can handle liquid or semi-solid fat, grease, and cooking oil, the rest of your home’s plumbing system cannot. “The biggest no-no is grease,” Vandepoll says. “It may look harmless when it’s a warm liquid you can run through your disposal, but it will cool quickly in a dark, hidden pipe and become a sticky mess that can either create a blockage on its own or grab other debris as it passes through.”
According to Barnes, fats cause the same problems. “If you remove the excess fat off your pork roast, for example, and then grind it up in your disposal, you just created a greasy mess that can cause problems downstream,” he says.
PRO TIP
“Grease should always be cooled in a container and then thrown in the trash. Some towns and cities even offer free caps that fit on soup cans so you can collect grease, cool it down, and put it right in the trash, can and all.”— Hendrick Vandepoll, Master Plumber and Co-Owner of Service Force Plumbing in Rockville, MD
I’ve learned the hard way that pouring bacon grease down the sink is a bad idea—my kitchen drain clogged up within a week! The science behind this is simple: grease solidifies as it cools, sticking to pipe walls and trapping other debris. According to the Environmental Protection Agency, fats, oils, and grease are responsible for about 47% of sewer blockages in the U.S. To avoid this, I now keep an old coffee can under the sink for grease. Once it’s full, I seal it with a lid and toss it in the trash. If you’re looking for a practical tip, try freezing the grease first—it hardens quickly and makes disposal cleaner and easier.
2. Pasta, Rice, and Oats
Delicious on your plate, but a problem in your plumbing, pasta, rice, and oats continue to swell with water, even after cooking. Toss them in the trash unless you’re willing to risk a clog.
These starchy foods absorb water like sponges, even after they’re cooked. I once made the mistake of rinsing a pot of leftover rice down the disposal, thinking it’d be fine. Big mistake—it turned into a gloopy mess that took a plunger and some elbow grease to fix. The reason? Starches like pasta and rice can expand up to twice their size in water, creating a thick paste that clogs pipes. Instead of risking a plumbing bill— which can easily run $200 or more for a clog—scrape these leftovers into the trash or compost. If you’re composting, just make sure the grains are buried deep to avoid attracting pests.
3. Bones
Even though very small bones will probably pass through without a problem, it’s safest to keep all bones out of your garbage disposal. These hard items can break your disposal, or clog your plumbing.
Bones are tough—literally. They can dull or chip the blades of your disposal, and larger ones might jam the unit entirely. I’ve seen friends try to grind up chicken bones, only to hear that awful grinding noise that signals trouble. Repairing a damaged disposal can cost anywhere from $150 to $300, depending on the model. If you’ve got bones from dinner, toss them in the trash or, better yet, save them for making stock. Boiling bones for broth is a great way to get extra use out of them, and it keeps your disposal safe.
4. Seafood Shells
Like bones, seafood shells shouldn’t be ditched down the disposal. Whether it’s clams, oysters, mussels, or lobsters, these hard casings can damage the disposal’s blades or cause a clog.
Those hard, jagged shells from shrimp or lobster can wreak havoc on your disposal’s blades, and they don’t break down easily in pipes either. I learned this after a seafood boil when I thoughtlessly tossed shrimp shells down the drain—my sink smelled fishy for days! Shells can also harbor bacteria, adding to the stink. Instead, bag them up and toss them in the trash, or add them to a compost pile if you’re set up for it. Fun fact: crushed oyster shells can be a great calcium boost for garden soil, so consider grinding them up (not in the disposal!) and mixing them into your flower beds.
5. Potato Peels
It’s super convenient to peel spuds over the kitchen sink, but don’t send those peels down the drain. Potato peels turn into a gluey mass inside your plumbing pipes, and pose a major clog risk.
“Potatoes and potato peels being put down the drain are a big reason that the day after Thanksgiving is one of the busiest plumbing crisis days of the year, along with grease,” Barnes explains. “Your garbage disposal is great at turning starchy foods into a sticky mess that can either clog your pipes…or grab onto other debris as it passes through.”
Thanksgiving is notorious for plumbing issues, and I can see why—those mashed potatoes are a killer! Potato peels are high in starch, which turns into a paste when wet, sticking to pipes like glue. Plumbers report that starchy foods like these contribute to about 20% of holiday-related drain clogs. My go-to trick is to peel potatoes into a bowl or directly into the trash. If you’re composting, potato peels are great, but chop them finely to speed up decomposition and avoid a smelly pile.
6. Broken Glass or Metal
If metal or glass falls into your garbage disposal, don’t turn the appliance on. Instead, cut off power to the unit and switch off the disposal at the unit under the sink, then try to fish out the interloping item with a fork, grabber, or hook. If that’s not possible, put on gloves to protect your hands and carefully retrieve the item. Always make sure the garbage disposal is completely turned off before attempting to retrieve an item from the sink.
I once dropped a spoon into the disposal and nearly made the mistake of turning it on—thankfully, I caught myself in time. Metal or glass can shatter blades or get lodged, leading to costly repairs or even a full replacement, which can set you back $100 to $500. Safety is key here: always unplug the unit or flip the breaker before reaching in. A handy trick I use is keeping a pair of long kitchen tongs nearby for fishing out stray items—it’s safer and less stressful than poking around with your fingers.
7. Eggshells
There’s some dispute about whether or not eggshells are safe for the garbage disposal, but according to Barnes, they’re another big no-no. You’re better off composting them, crushing them up and mixing them into your garden soil, or disposing of them in the trash.
I used to think eggshells were fine because they’re small and brittle, but Barnes set me straight. The thin membrane inside the shell can wrap around blades, and the gritty bits can build up in pipes over time. Instead of risking it, I crush eggshells and sprinkle them around my garden plants—they’re a natural source of calcium and can deter slugs. If you don’t garden, just toss them in the trash. It’s a small step that saves you from potential plumbing headaches down the line.
8. Chicken Skin
Removing skin before cooking chicken is sure to reduce your fat intake, but don’t toss the skin down your garbage disposal. It can easily clog your plumbing—and brings unnecessary germs and stink to your sink.
Chicken skin is fatty and slimy, a perfect recipe for clogging pipes and making your sink smell like a butcher shop. I made this mistake once after prepping a roast chicken, and the lingering odor was not pleasant. The fat content in chicken skin also adds to the grease problem in pipes. Instead, wrap it tightly in a plastic bag and toss it in the trash to keep things clean and odor-free. If you’re into zero waste, consider rendering the fat for cooking—it’s a tasty alternative to clogging your drain.
9. Fibrous Vegetables
While most vegetables can safely pass through the garbage disposal, fibrous veggies, including artichoke, celery, rhubarb, lettuce, kale, cornhusks, onion skins, asparagus, and chard tend to get tangled around the disposal’s blades. “These are actually hard on your garbage disposal itself and can shorten its lifespan,” Vandepoll says. Instead, deposit these veggies in your compost bin, or toss them in the trash.
Fibrous veggies are like the stringy nemesis of your disposal. I once tried to grind up celery stalks and ended up with a jammed unit that took forever to unclog. The tough fibers can wrap around the blades, straining the motor and potentially burning it out. A new disposal can cost $100 or more, so it’s worth being cautious. I now chop these veggies into small pieces for composting—they break down well and add nutrients to the soil. If composting isn’t your thing, just bag them up for the trash to keep your disposal humming along.
10. Produce Stickers
It’s fine to put citrus, apple, or banana peels into the garbage disposal, but be sure to remove any produce stickers before you do. Stickers are likely to adhere to the disposal’s blades, or the inside of your pipes.
Those tiny stickers on fruit seem harmless, but they’re surprisingly sticky and don’t break down. I’ve found a few stuck in my disposal over the years, and they’re a pain to remove. They can also cling to pipes, collecting debris over time. To avoid this, I make it a habit to peel off stickers while rinsing fruit—it only takes a second. If you accidentally send one down, don’t panic; just be mindful to check next time to keep your disposal running smoothly.
11. Medication
Tossing unused medication down the garbage disposal might seem like a smart way to dispose of controlled substances, but putting drugs into your plumbing can negatively impact the water supply. Instead, the FDA recommends removing the drugs from their packaging, putting them in a plastic bag with an unappealing substance (think used kitty litter, or dog waste), then disposing of the bag in the trash.
Dumping meds down the drain is a bigger deal than I realized—it can contaminate local water systems, harming wildlife and even ending up in drinking water. The FDA says about 5% of water pollution comes from improper medication disposal. I’ve started keeping a small ziplock bag for old pills, mixing them with coffee grounds or cat litter before tossing them. Many pharmacies also offer take-back programs, which are a safer bet. Check with your local pharmacy to find a drop-off spot—it’s an easy way to keep your community’s water clean.
12. Fruit Pits
When you’re snacking on fruit and are left with just the pit, deposit it in your compost or garbage. While garbage disposals are generally pretty durable, this hard center seed will likely dent or break the blades.
Fruit pits, like peach or avocado stones, are way too tough for your disposal. I once tried grinding a mango pit (bad idea), and the unit made a horrible grinding sound. Those hard pits can damage blades, leading to repairs that aren’t cheap. Instead, I toss pits into my compost bin—they take a while to break down, but they’re better there than in your plumbing. If you don’t compost, just throw them in the trash. It’s a small step to save your disposal from a big problem.
13. Coffee Grounds
Coffee grounds seem fairly innocuous when faced with the garbage disposal, but it’s actually one of the worst things you could put down the drain. Eventually the grounds build up and form a sludge (like the dregs in your coffee pot), which creates a clog. Instead of tossing them into the trash, add coffee grounds to your garden soil or compost bin.
I’m a coffee lover, so I used to rinse grounds down the sink without a second thought—until I learned they can form a sludgy mess that’s tough to clear. Plumbers say coffee grounds are a top culprit for clogs, contributing to thousands of service calls each year. Now, I sprinkle used grounds around my roses—they love the nitrogen boost, and it keeps my pipes clear. If you’re not a gardener, seal them in a bag for the trash to avoid any drain drama.
14. Sauerkraut
Be careful when you’re scraping plates after a barbecue! Sauerkraut is a delicious condiment, but it’s also a prime offender for clogging a garbage disposal. Like potato skins, sauerkraut will form a gelatinous goo in the drain.
Sauerkraut’s tangy goodness doesn’t translate well to your plumbing. Its high water content and fibrous texture can turn into a sticky sludge, especially when mixed with other debris. I learned this after a summer barbecue when my sink backed up—yuck. To avoid this, I scrape sauerkraut into the trash or compost bin. If you’re composting, mix it well with dry materials like leaves to prevent a smelly pile. It’s a simple habit that keeps your drain flowing freely.
15. Nuts
They might be small, but nuts spell disaster when they meet with a garbage disposal. Think about it: The garbage disposal’s grinding and mashing actions are similar to those for making nut butter. This pasty concoction won’t do your hardworking appliance any favors.
Nuts may be tiny, but they’re a nightmare for disposals. I once tossed a handful of almonds down the drain, thinking they’d grind up easily. Nope—they turned into a peanut butter-like paste that gummed up the works. The oily, sticky residue can coat pipes and trap other debris, leading to clogs. Instead, I save nut scraps for baking or toss them in the trash. If you’re into DIY, you can even grind them in a blender for homemade nut butter—just keep your disposal out of it!