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Refilled Plastic Water Bottles May Have More Germs Than Your Toilet Seat

It's a water bottle. But it could be a bacteria bottle too.

We know that pretty much everything gets covered in fecal matter especially your iPhone, your toothbrush, your shoes, the weights at the gym...

So it's not shocking that reusable water bottles, left unwashed, can become a breeding ground for bacteria and a safe haven for poop particles. Whether screw top or squeeze, bottles that go days between cleanings can leave us gulping down germs with every drink.

An analysis last year from New Jersey-based EmLab P&K, an environmental testing company, found liquid carrying bottles carrying an average of more than 300,000 colony-forming units of bacteria per square centimeter.

 That's roughly six times the quantity of such bacteria found on pet water bowls, the study said, and just slightly less than on the toothbrush holder sitting unwashed near your dirty toilet.

For the study, conducted for the site TreadmillReviews.net, researchers swabbed 12 water bottles used by athletes that have not been cleaned in a week. They used different types of bottles: Three squeeze top, three slide top, three screw top and three straw top.

The EmLab P&K study isn't peer reviewed, but its findings are bolstered by comments from Charles Gerba, the renowned Univ. of Arizona professor better known as "Dr. Germ." 

"Your hands may pick up viruses from touching various surfaces, which then get transferred to the bottle and eventually to your mouth," Gerba told Shape.

Your mouth contains bacteria that can get into your bottle via backwash, but as Gerba told Self, your own germs that were already in your mouth won't harm you. New germs can, though. Those can come from sharing a bottle with another person, or from touching something gross — say, fitness equipment at the gym with fecal matter on it — and then opening your bottle.

Slide-top bottles in the study were by far the dirtiest, carrying some 933,000 colony forming units per square centimeter. Straw-bottles only carried a mere 25.4 units per square centimeter. 

Stainless steel bottles, like the kitchen grade stainless steel Ice Shaker Cup, are naturally anti-bacterial and don't develop germ-harboring cracks, making them perhaps your best bet for a clean water bottle or protein shaker cup.

To clean them, Hand-wash your bottle by filling it halfway with hot water and adding unscented dish soap. After a few minutes, rinse the soapy water completely away using warm water.