Study Shows Which Water Bottle Germaphobes Should Be Drinking Out Of


Taking a reusable water bottle with you to the gym might get you points for sustainability, but it’s probably not helping you out healthwise. No, this isn’t about BPA — it’s about germs. So, so many germs. According to analysis done by the team at, the cleanliness of your water bottle is comparable to your toilet (not your toilet, Rob, but everyone else’s).

The study analyzed the germ counts in several different types of water bottles after being used for a week without washing, and compared the numbers to data retrieved from an NSF study of germ counts of common household objects. The results are enough to make you run your favorite hydration device through the sanitizing cycle on your dishwasher multiple times: the average athlete’s water bottle contains 313,499 colony-forming units (CFU) per square centimeter. The average pet toy, by comparison? 2,937 CFU/sq cm.

Luckily, the team also analyzed the water bottles to find out which type of common water bottle tends to be the cleanest. Among slide-top, squeeze-top, screw-top, and straw-top, the straw-top by far ranked the best, with a measly 25.4 CFU/sq cm. The clear loser in the scenario was the slide-top water bottle, with 933,340 CFU/sq cm.

Why the huge difference? The team speculates that it’s because water goes to the bottom of a straw when it’s not in use, rather than remaining around the top of the bottle and attracting moisture-loving germs. Still, even the straw-top contains only 1.2 CFU/sq cm less than the average home toilet seat.

But, okay. Not all germs are created equally. The study also accounted for that, making sure to look at the overall makeup of the bacteria found on each type of water bottle. The bottles with the highest concentration of gram-negative rods — the type of bacteria that’s the most harmful and often antibiotic-immune — were the squeeze-top and the screw-top, coming in at 99% and 98% respectively.

And again, straw-top water bottles left the competition in the dust: just 8% of the bacteria analyzed were gram-positive cocci, which can cause strep and staph infections, while the remaining 92% of the bacteria were the usually harmless gram-positive rods.

It’s eye-opening data, but the team at Treadmill Reviews isn’t attempting to scare you into giving up reusable water bottles forever. What they want to do is raise awareness of water bottle cleanliness, and offer practical tips for future hydration. First, obviously, you should switch to a straw-top bottle if you’re truly ready to do something about the germ issue. But beyond that, you should also make sure your bottle is stainless-steel, if possible, and also free of any tiny nooks or crevices that could be hard-to-clean germ hotspots.

And speaking of cleaning, make sure to run your bottle through the dishwasher or give it a thorough hand wash after your workout — don’t let it sit half-empty in your gym bag for weeks. If you really want to go the sanitization route, you can dunk it in a weak bleach solution of one teaspoon of bleach to one quart of water.