10 Things You Should Never Put Down the Drain (They Can Seriously Damage Your Pipes)

Your kitchen sink might seem like it can handle just about anything. You rinse your plate, flip the garbage disposal switch, and expect everything to disappear without a second thought.

But while disposals are built to handle small food scraps, they’re not designed to process everything we send their way. Over time, certain foods and substances can build up, damage the blades, or clog your pipes entirely, often without you noticing until there’s a problem.

Some of the biggest offenders aren’t obvious either. They’re everyday items many people assume are harmless. Here are 10 things you should never put down the drain and why it matters.

1. Cooking Oil and Grease

Grease might go down the drain as a liquid, but it doesn’t stay that way. As it cools, it solidifies and sticks to the inside of your pipes. Over time, that buildup narrows the space for water to flow, leading to slow drains and stubborn clogs.

It’s one of the most common causes of plumbing issues and one of the easiest to prevent by letting grease cool and disposing of it in the trash instead.

2. Coffee Grounds

Coffee grounds seem small enough to wash away, but they tend to clump together inside pipes. Instead of breaking down, they settle and accumulate, creating dense blockages that water can’t easily pass through.

Even if your sink seems fine at first, this buildup can quietly turn into a much bigger problem over time.

3. Bones

Bones are simply too hard for a garbage disposal to handle. Even small ones can damage the blades, strain the motor, or cause the system to jam entirely. If something feels tough in your hand, it’s a good sign it doesn’t belong in your disposal.

4. Fruit Pits and Seeds

Items like avocado pits, peach stones, and cherry seeds don’t break down in a disposal. Instead, they bounce around, potentially damaging internal components or getting lodged where they don’t belong. These are best tossed in the trash or compost.

5. Eggshells

Eggshells are often debated, but they can cause more harm than expected. The thin membrane inside can wrap around disposal parts, while the crushed shells create a gritty residue that dulls blades and contributes to buildup. Over time, they can also trap odors if they linger in the system.

6. Stringy Fruits and Vegetables

Fibrous foods like celery, banana peels, asparagus, corn husks, and artichoke leaves are especially problematic. Their stringy texture can wrap around the disposal’s blades, leading to jams or reduced performance. These are better off in the compost bin than your sink.

7. Starchy Foods

Pasta, rice, bread, and oatmeal may seem soft, but they expand when exposed to water. Inside your pipes, they become sticky and dense, clinging to surfaces and forming blockages that are difficult to clear. Even small amounts can add up quickly.

8. Seafood Shells

Shells from crab, lobster, oysters, or mussels are far too hard to grind. They can damage the disposal or get stuck, potentially shutting it down completely. These should always go straight into the trash.

9. Potato Peels

Potato skins are thin enough to slip past the disposal blades without being fully broken down. Once they move further into the pipes, they can clump together and block water flow almost immediately. They’re one of the more common causes of sudden clogs.

10. Harsh Cleaning Chemicals

It might seem like pouring bleach or drain cleaner down the sink will help keep things clean, but over time, these harsh chemicals can damage your disposal’s internal parts and your plumbing system. Gentler cleaning methods are safer and more effective in the long run.

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