A garbage disposal is an electronic device fitted to the underside of a kitchen sink. It uses blades to grind food waste into pieces small enough to be carried away in the plumbing system. It is a clean, fast, eco-friendly way to get rid of your kitchen waste, as food goes into the water system and not a landfill.

To ensure the long life of your garbage disposal, avoid putting these items down the drain.

Maybe you’ve heard a myth that coffee grounds are good for your plumbing system and keep away bad odors. But actually, they’re one of the worst things that you can put down the drain, as they form into a sludgy mess and can block your pipes.

Potato peels can create a sticky, gluey mess that causes plumbing blockages. After the peels pass through the blades of your garbage disposal and into pipes, they get waterlogged and break down into a viscous liquid.

Produce is usually safe to dispose of but certain fibrous veggies, such as celery, rhubarb, pumpkin innards, chard, kale and asparagus may get tangled up in the blades and cause them to malfunction.

Starchy foods like pasta, rice, oats and beans expand with water. This swelling can cause food to become lodged in a garbage disposal’s blades or kitchen pipes, leading to clogs and preventing proper sink drainage.

Things like oils, butter, poultry skin and bacon grease might slip down your disposal with ease but these substances solidify and stick in your pipes. Their accumulation can lead to significant plumbing issues such as backups or leaks.

Some experts say eggshells are relatively safe and may even help garbage disposal blades stay sharp, but the problem is the membrane just beneath the eggshell. It can wrap around the blades. Onion skins can do the same or slip past the blades intact, forming a clog in your pipes.

If the kitchen sink’s the closest water source to a kid’s art project or maintenance work site, it might be tempting to wash hands or supplies there. However, you should avoid sending paint and harsh chemicals down your drain as they will damage your disposal and the pipes. Oil and latex paints can coat your pipes before hardening and causing blockages.

Nut butters are made by grinding nuts into a paste with food processor blades. Avoid putting large quantities of nuts down your disposal as they can become lodged in the pipes and cause clogs.

A garbage disposal is designed to handle soft food waste. Peach pits, mango seeds and other large stones may be too hard on your device. They are very tough and may overwork, bend or break your blades, or burn out the motor. Avocado and peach pits are also large enough to form clogs. Even smaller pits and seeds, such as cherries and grapes, can cause problems.

Shellfish, such as oysters, crabs, lobster and even shrimp, come with a hard exoskeleton that can be tough on disposal blades and cause damage to pipes. Big bones, such as ribs, are definitely not meant for a garbage disposal and may even break the blades. The jury is still out on small bones. Some experts say this is a no-no, while others say the device is powerful enough to handle them.

It goes without saying that non-food items, such as napkins, paper towels, wrappers, foil and cellophane, should go in your trash and not your garbage disposal, but sometimes silverware may fall in or a glass may break in the sink. If your disposal is turned on with these items in it, it can lead to clogs or the bending or breaking of its blades.

Since everything ground up by your disposal eventually gets into the water supply, it’s a no-brainer to avoid throwing out medicine with your garbage disposal. Check the label to see if there are disposal instructions and follow them. Consult a local pharmacy or health center to see if they take back expired or unused medication.