Reusable bottles are healthier for you and more environmentally friendly but a new study conducted by reveals that reusable water bottles can harbor huge levels of germs and potentially harmful bacteria if not cleaned properly.

To determine the levels of bacteria that may be present, researchers swabbed the lids of reusable water bottles used by athletes and then had the samples tested at an independent lab. A total of 12 swabs were taken from four different water bottles with different tops (straw-top, screw-top, slide-top, squeeze-top), and the results were shocking.

On average, unwashed reusable drinking containers may be crawling with more than 300,000 colony-forming units per square centimeter (CFU/sq cm). What's that mean for non-scientist folks? One way to look at it is that drinking from the average reusable bottle is much worse than licking a dog's toy which has just 2,937 CFU. Here's a look at some of the other comparisons the study drew:

reusable water bottles

It looks like drinking from certain reusable containers can be dirtier than other surfaces like cutting boards and kitchen sinks. Even so, reusable bottles, when washed properly and not left in your gym bag for days, are the best alternative to plastic bottles. After all, reusable water bottles that are BPA-free are better for you and for the planet. Stainless steel bottles are also a great solution to plastic.

It's Time to Wash Your Reusable Bottles 

The moral of the study couldn't be more clear. After each use, don't forget to give your reusable bottle a good rinse. Throw it in the dishwasher, wash it in warm soapy water, clean it the all-natural way with vinegar or use cleaning tablets made specifically for disinfecting your reusable water bottle. Whatever you do, just make sure you keep it clean, otherwise, you could be drinking out of the equivalent of a toilet seat.