The runner’s high is an almost-transcendent state. Your muscles burn, your blood pumps, your arms and legs move in perfect sync. Sweat trickles down your face, but you hardly notice. You realize you’re thirsty, and you barely break stride as you grab your reusable water bottle and take a swig of – germs. That’s right.

Thousands of moisture-loving bacteria may be crawling on your favorite refillable drinking container.

And the act of quenching your thirst while you exercise could potentially make you sick.

Since most people can’t finish a workout without their reusable water bottle, our team decided to investigate the allure of these captivating canteens. Our team swabbed the lids of reusable water bottles used by athletes and had the samples tested at an independent lab to determine the types and levels of bacteria present. Are the containers squeaky-clean or crawling with germs? We’ll let the results speak for themselves …Don’t worry – we’re not recommending that you toss your container or switch to bottled water. We care about the environment, your health, and the nation’s landfills. We simply think you should be aware of the potential for contamination.

Our hope is that our findings will help you make informed choices, whether that means choosing a new refillable bottle or simply being more conscientious about cleaning the containers you own. 


Based on the 12 water bottles we tested, we found that reusable drinking containers may be crawling with an alarming number of viable bacteria cells: more than 300,000 colony-forming units per square centimeter (CFU/sq cm).

What exactly does that mean?

To put it bluntly, drinking from the average refillable bottle can be many times worse than licking your dog’s toy.

Perhaps you’ve seen viral posts on social media showcasing horrifying photos of reusable drinking containers covered in mold. However, the bacteria we tested for aren’t visible to the human eye – so you don’t even know when you’re consuming them (and in this situation, ignorance is not bliss.)


When you’re exercising, you want a water bottle that’s durable, easy to use, and spill-proof – and hopefully not crawling with germs. We lab tested four types of containers to see how each measures up in the creepy-crawly department.

Some people favor slide-top bottles for the ease factor – just slide the lid shut and don’t worry about spills. However, when it comes to germ content, these containers make the biggest splash.

The spot your lips touch is absolutely writhing with bacteria: over 900,000 CFU/sq cm on average. Yikes!

The squeeze-top bottles are crawling with nearly 162,000 CFU/sq cm, while the screw-top containers host just under 160,000 CFU/sq cm. While they are aren’t as bacteria-ridden as the slide-top lids, drinking from these bottles can still be worse than eating a meal from your pet’s dish or lapping up water from your kitchen sink.

Another big surprise? The straw-top bottles we tested contain a mere fraction of the bacteria of other bottles – just 25 CFU/sq cm. This may be because water drips to the bottom of the straw rather than sticking around to attract moisture-loving germs. However, that is only 2 CFU/sq cm less than the average home toilet seat.


If you can remember anything about biology class (aside from those scary dissection projects), you might recall that the planet is home to numerous types of bacteria.

Many are harmless, some are beneficial – and others can make you sick.

The different types of bottles we tested each hosted a unique combination of bacteria types. Surprisingly, 99 percent of the germs on the squeeze-top bottles and 98 percent of the germs on the screw-top bottles are the bad kind – gram-negative rods (of which E. coli is one example.) These types of germs have been known to cause conditions such as pneumonia and blood infections in health care settings, and they can even resist antibiotics.

And remember the slide-top bottles that hosted the most germs by far? It turns out that half of the bacteria on those containers have the potential to harm. Along with gram-negative rods, the bottles harbored gram-positive cocci, which can lead to skin infections, pneumonia, or blood poisoning. Amazingly, the straw-top bottles (which barely contained any bacteria to begin with) mostly host harmless germs.


The urge to run is natural and powerful – as is the desire to suck down copious amounts of water both during and after exercise. When working out, drinking from glasses isn’t always practical, and disposable water bottles are far from ideal. However, the results of our reusable water bottle germ tests are fairly alarming: Over 60 percent of the germs we found just might make you sick.

We’re treadmill experts constantly in search of the best treadmill, not microbiologists, but we’ve learned a few things about refillable water containers through this project. Based on our test results, we suggest opting for a straw-top bottle, both for the low prevalence of bacteria and the lack of harmful germs. While most treadmills from popular brands (ie. SoleNordicTrack, etc.) are well equipped for water bottles, the straw-top may not necessarily be practical, so you’ll need to be flexible.

We also know that when it comes to water bottles and bacteria, stainless steel is a better choice than plastic. Additionally, water bottles without crevices and tough-to-clean spots are less likely to host germs. Are you loath to give up your favorite container? Don’t let your half full bottle sit in your gym bag. Instead, be sure to run it through the dishwasher or hand wash it thoroughly after every use. You can even use a weak bleach solution (one tablespoon of bleach per quart of water) to sanitize your water bottle.

Armed with a not-so-germy water bottle, you can turn your attention to what’s really important: your daily run.


We swabbed three water bottles for each different type of water bottle (screw-top, slide-top, squeeze-top, and straw-top) for a total of 12 swabs. Each water bottle had been used by an athlete for a week without being washed. EmLab P&K performed all laboratory testing.


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Q: What are the best treadmills with water bottle holders?

A: Having a water bottle holder is a must when exercising on a treadmill. At this point, whether it’s a foldable treadmill, walking treadmill, or treadmill for home, most treadmill types come with water bottle holders built in.

The top 5, best rated treadmills you can find that have a water bottle holder built-in are Peloton Treadmill by Peloton, Nordictrack Commercial 1750 by Nordictrack, the Sole F80 by Sole, the horizon 7.0 at treadmill by Horizon, or the ProForm Smart Pro 9000 by ProForm.