If you've ever shared a house in your life, you'll know all too well that it can get filthy.
We're talking mounds of unwashed dishes, dirty clothes everywhere and some pretty smelly food in the fridge that's probably been there since last Christmas.
However it turns out the place you need to be most wary of in your share house is the bathroom and more to the point, where you leave your toothbrush.
According to a new study presented at the American Society for Microbiology, there's a pretty massive chance that if you share your bathroom with other people, it's likely there's someone else's faeces nestled on your bristles.
Researchers examined more than 135 toothbrushes from students in a shared dormitory, who were using communal bathrooms - and the results are gross.
They found that over 60 per cent of the toothbrushes were contaminated with faecal matter and disgustingly, there was an 80 per cent chance that the bacteria was from someone else.
The results didn't change when the toothbrushes were cleaned with hot water or mouth wash.
The researchers explained that faecal matter from the toilet can spray up to six-feet when the toilet is flushed and can catch in the bristles of your toothbrush.
Lead researcher Lauren Aber of Quinnipiac University said that using a toothbrush cover may seem like a good idea, but even that won't protect you from the dirt.
“Using a toothbrush cover doesn’t protect a toothbrush from bacterial growth, but actually creates an environment where bacteria are better suited to grow by keeping the bristles moist and not allowing the head of the toothbrush to dry out between uses," she said.
Lauren also told Yahoo Health that there’s the same risk even in your family home.
"You don’t think of it as a problem when they’re your family members,” she said.
"It doesn’t really matter who the people are — you’ll still sharing the [bacterial] flora. The results are most likely relevant to any situation where there’s a shared bathroom.”
She says that in a home setting, there can be greater spread of germs, especially if brushes are stored in the same holder.
“That can allow for lateral transfer of bacteria, because toothbrushes could get knocked together or water sprayed in between brushes.”
Previous studies have suggested soaking your toothbrush in mouthwash for 20 minutes, shielding it by keeping it upright inside a medicine cabinet, closing the toilet lid before you flush and allowing your brush to completely air-dry before using it again.