6 Overlooked Things You Should Never Flush Down Your Toilet

The modern toilet is one of the most incredible and underappreciated conveniences of our homes. We take it completely for granted: we flush, and the waste simply disappears. But that “out of sight, out of mind” convenience can lead to some major, messy, and incredibly expensive problems if we treat our toilets like a magic trash can.

There is a simple, golden rule of plumbing: your toilet is only designed to handle human waste and toilet paper. That’s it. Flushing anything else is a risky gamble that can lead to a destructive clog in your home’s plumbing or contribute to a massive blockage in your city’s sewer main. When that happens, your only solution is a stressful, and often costly, call to a professional plumber.

The good news is that most of these catastrophic clogs are completely preventable. It all starts with knowing what you should never, ever flush. Here are six of the most common offenders.

1. So-Called “Flushable” Wipes

This is, without a doubt, the number one enemy of modern plumbing systems. The packaging might say “flushable” and “sewer-safe,” but the reality is that these wipes do not break down in water the way toilet paper does. They are made with synthetic fibers that are designed to be durable. When you flush them, they can clump together in your pipes, creating a dense, stubborn clog that a simple plunger can’t fix. On a larger scale, these wipes are the primary ingredient in the giant, city-blocking sewer blockages known as “fatbergs.”

2. Paper Towels and Facial Tissues

Many people assume that any paper product is fine to flush. This is a costly mistake. Paper towels and facial tissues are engineered to have “wet strength”—they are designed to hold together when they get wet. Toilet paper, on the other hand, is specifically designed to break down and dissolve quickly in water. Flushing a paper towel is essentially the same as flushing a small piece of cloth down the drain. It doesn’t dissolve and can easily get caught, starting a blockage.

3. Dental Floss

It seems so small and harmless, but that thin string is a major menace to your plumbing. Dental floss is not biodegradable and is incredibly strong. When you flush it, it’s like sending a tiny net down your pipes. It can wrap itself around other debris, snag on the inside of the pipe, and create the perfect starting point for a much larger clog to form. Always toss your used floss in the trash can.

4. Cotton Swabs and Cotton Balls

Much like paper towels, cotton products are designed to be absorbent and to hold their shape. They do not break down in water. When flushed, cotton swabs and balls will clump together, absorb a huge amount of water, and can easily get lodged in the twists and turns of your drain lines. These are very common causes of toilet clogs that require professional removal.

5. Fats, Oils, and Grease (FOG)

Most of us know not to pour hot cooking grease down the kitchen sink. But some people think the toilet is a safer alternative. It is not. When you pour hot, liquid grease down the drain, it eventually cools as it travels through your pipes. As it cools, it congeals and solidifies, coating the inside of your pipes with a thick, sticky residue. This greasy coating then acts like flypaper, trapping every other piece of debris that comes down the line until a massive, hard-to-remove clog is formed.

6. Any Kind of Medication

This final point isn’t about protecting your pipes; it’s about protecting our environment and our water supply. Flushing old, expired, or unused medications is a serious environmental hazard. Wastewater treatment plants are not designed to filter out the complex chemical compounds found in pharmaceuticals. These drugs can pass through the system and end up in our rivers and lakes, where they can harm aquatic life. The U.S. Food & Drug Administration (FDA) provides clear guidelines on how to dispose of old medications safely, which often involves using a local pharmacy’s drug take-back program.

When in doubt, remember the simple rule: the only things that should ever be flushed are the “Three P’s”- pee, poo, and (toilet) paper. Everything else belongs in the trash.