Go to any drugstore or supermarket, and it’s easy to find wipes and other supplies labeled “flushable.” It’s totally fine to flush those wipes down the toilet, the packaging claims. No problem at all.

But according to sewage plants and wastewater experts, those so-called “flushable” products are actually a big problem. They might be flushable enough to snake through the toilet’s plumbing, but they don’t disintegrate before they reach the various channels, tanks, and propellers at sewage plants. Instead, they clump up on everything they hit — clogging up the system and, in some cases, even breaking heavy pieces of machinery. Employees have to regularly hand-chisel wipe-boulders out of the innards of the sewage plant.

The Verge Science video team went to see the damage wipes can do — and got up close and personal with the bits of fabric that cost cities millions and millions of dollars each year to manage. Watch our latest video to see what we discovered.