Washing hands
Credit: Ulrich Baumgarten / Getty Images

Can you guess the dirtiest things you touch on a regular basis? Hint: it's not your mop, and it's surprisingly not your toilet seat. It turns out the germiest places are the last ones you'd think of, which makes sense, because we they're the same ones we often forget to clean.

"Everyone's afraid of butt-borne diseases, but toilet seats tend to be the cleanest thing in the bathroom because we clean them so often," Charles Gerba, a professor of microbiology at the University of Arizona recently told TIME. The real bathroom germ offenders are your hand towels and, wait for it…your toothbrush holder, he says.

"Bacteria like to grow in wet, moist conditions," he explains. Couple that with the fact that most people don't wash their hands properly, and voila! Your hand towels become the ideal breading ground for bacteria.

To combat the spread of germs, Gerba suggests washing all towels—including the one you grab after showering—after two days of use. And toothbrush holders? Well, the problem is that people rarely clean them. A 2011 report from NSF International found Coliform bacteria (microorganisms including Salmonella and E. coli) on 27% of toothbrush holders.

Speaking of E. coli, you can pretty much count on finding it camping out on the handles of supermarket carts. "Almost 100% of them are home to E. coli because people are constantly touching the handles after holding raw food products," Gerba explains. But that doesn't mean you shouldn't use them. Instead, worry about disinfecting your hands when you're done shopping.

After supermarket carts, Gerba identifies that poor old sponge sitting next to your sink as your biggest germ repository in the kitchen. "It's probably home to hundreds of millions of bacteria," he says. NSF research confirms this with a study that found that 75% of home dish sponges and rags contained Coliform. Gerba recommends ditching the sponge in favor of a brush, or a cleaning tool you can throw into the dishwasher to disinfect.

And last but not least, is the most unsettling of them all: your cell phone. Studies have found that one in six phones is contaminated with fecal matter. Ick! Luckily it's nothing a good disinfectant wipe can't handle.

That's not all. Plenty more everyday items likely make the list: shoelaces, purses, car keys, keyboards, and so on. Gerba suggests warding off their germy advances simply by making a habit of washing your hands (or using sanitzer) the moment you walk into the house.