We’ve lost count of the amount of times we must have gone to quickly refill a water bottle without washing it. Quickly topping up before leaving the house, or after the gym, or stay hydrated at work.

But we might think twice about that now, thanks to new research from treadmillreviews. According to tests done by these guys, our water bottles could contain thousands of moisture-loving bacteria!

They discovered that refillable water bottles can contain more than 300,000 colony-forming units per square centimeter (CFU/sq cm).

refill a water bottle without washing - water bottle bacteria

To put that into perspective, a chopping board in your kitchen may contain up to 6.8 CFU, whereas your pet’s bowl could have as many as 47,383 CFU. Still, that’s no where near the 300,000 found on your water bottle is it?! Even a toothbrush holder, with 331,848 CFU only just overtakes it.

To top it all off, apparently an average toilet seat has 1,600 germs per 100cm². This makes your handy hydration tool potentially dirtier than a loo. Gross.

Over 60% of the germs the researchers found on an average water bottle could make you sick. So the moral of the story? Wash your bottles thoroughly! And when buying a new refillable bottle, try and go for stainless steel over plastic.