You may think that you’re saving the planet by reusing your water bottle, but the truth is you are putting the dirtiest things in your mouth.
According to studies, when left unwashed reusable water bottles can become a breeding ground for bacteria and a safe haven for poop particles. Whether plastic or metal, screw-top or squeeze, bottles that go days between cleanings can leave us gulping down germs with every drink.
It was New Jersey-based EmLab P&K, an environmental testing firm, that found water bottles carrying an average of more than 300,000 colony-forming units of bacteria per square centimeter. That’s roughly six times the amount of such bacteria found on pet bowls, the study said, and just slightly fewer than on the toothbrush holder sitting unwashed near your toilet.
“Your hands may pick up viruses from touching various surfaces, which then get transferred to the bottle and eventually to your mouth,” Charles Gerba, a professor of microbiology and environmental sciences, told Shape. According to Gerba, also known as Dr. Germ, your mouth contains bacteria that can get into your bottle via backwash, but your own germs already in your mouth won’t harm you.
However, new germs can and those can come from sharing a bottle with another person, or from touching something gross — say, an iPhone with fecal matter on it — and then opening your bottle.