The scientific answer to the over-under toilet paper debate

Some things—policy and healthcare, for example—warrant debate, while other widely contested subjects make you scratch your head. Take the conversation surrounding toilet paper. Yes, toilet paper.

Poll a room full of people about whether the toilet paper should hang over—when the loose end of the paper drapes over the roll, toward you—or under—when the loose end of the paper hugs the wall behind the roll—and you’ll get surprisingly strong opinions. In an informal poll of my friends, there was a strong sway toward over. Those who said under blamed it on cats that have unrolled entire rolls of toilet paper in the over position.

The over friends were passionate, though. “Under is just so wrong,” said a former colleague. “I used to think under, until [my husband] was like, ‘what are you thinking?!’ Now, I’m super aware of it and it’s become a pet peeve,” said another.

And as it turns out, these friends have some ground to stand on.

The argument for over

Usability: When hung over the roll, it’s easier to rip off a square of toilet paper. "Normally when people sit on the toilet, they want to apply minimal effort," Nicholas Bella, PhD, told VICE. "Which means people yank at the paper. When the toilet paper is at the front, it gives people more space within which to rotate their arm."

“If you think about toilet paper as it is dispensed, this makes sense,” says Mark Huntley, director of marketing at Go City Wide, a management company in the building maintenance industry. “When dispensing toilet paper with it rolling over the top, the paper naturally pulls away from the roll and when you tear off a piece, there is little chance of your dirty hand touching the roll," he explains.

Cleanliness: As Huntley mentioned, dirty hands on toilet paper, of course, means the transfer of harmful bacteria. "When you dispense toilet paper with the under method, as you attempt to pull the toilet paper off the roll, you usually have to get your hand a bit closer to the existing roll which results in a much higher likelihood of you touching the unused toilet paper,” says Huntley.

According to one study, toilet tissue dispensers already have 150 times more bacteria than the seats themselves. Most of these bacteria are not harmful as long as you wash your hands, but studies show people fail to wash their hands correctly 97 percent of the time. Also, consider that no one has the ability to wash their hands between using the restroom and touching toilet paper. That’s pretty gross—especially when you already have toilet plume to worry about.

Manufacturing: The original toilet paper patent from 1891 shows the toilet paper going over the roll. That's tough to argue with. And, finally, some less scientific proof that toilet paper belongs over the roll: Take a look at the pattern on your paper next time you’re in the bathroom. Any patterns or embossings are right-side up when hung over the roll. In the under position, patterns or embossings tend to be backwards or upside-down.