Your Reusable Water Bottle Is Harvesting Harmful Bacteria. Here’s How to Clean It

I admit it. I am guilty, as surely so many of us are. I forget to clean mine reusable water bottle regularly. I’m so busy trying to meet my daily water intake goal that I don’t take the time to think about the water I’m drinking. Am I risking my health?

Dirtier than your kitchen sink and your dog’s water bowl?

Imagine how many germs are in your kitchen sink right now. Now think about your dog’s water bowl. According to a recent study by New Jersey-based EmLab P&K, commissioned by Treadmillreviews.net, the average reusable water bottle contains 313,499 colony-forming germ units per square centimeter. That’s more than a kitchen sink (3,191 CFU) and a dog bowl (47,383 CFU) combined.

The study divided reusable water bottles into four categories: pinch top, straw top, slide top, and screw top. Three different bottles in each category were swapped out and tested, for a total of 12 bottles. Each water bottle was used unwashed for a week.

Of all the categories, the squeeze-top bottles were the most germ-rich with 99% harmful bacteria and 1% bacteria that cause streptococci and staph. Screw cap bottles were the second worst, with 98% harmful bacteria and about 2% harmless bacteria. Slide-top bottles had the greatest diversity of bacteria, with 33% harmful bacteria, 17% bacteria causing streptococci and staph, 17% harmless bacteria found in nature, and 33% harmless bacteria. Finally, straw tops contained 8% bacteria that cause streptococci and staph and 92% harmless bacteria. The study did not specify whether different bottle materials (metal, glass, or plastic) were tested.

It is important to note that this particular study has yet to be peer reviewed. However, University of Arizona microbiology and immunology professor Charles Gerba, “Dr. Germ” has confirmed the results of this study. He told Shape, “While the germs that come out of your own mouth probably won’t make you sick, the ones that get transferred from your hands to bottles will.”

Factors in the amount of germs

While the EmLab P&K study provided reliable results on the average CFU of germs living in our reusable water bottles, the results did not take into account what the bottle was made of and how often it was refilled. A peer-reviewed study by the International Association for Food Protection considered other factors.

The study collected and tested 90 water bottles; of which 65 were hard plastic bottles, 12 squeeze bottles, 10 metal bottles and three glass bottles. The outside and inside of each bottle was then blotted.

bottle material

Four bottle materials were tested: hard plastic, soft plastic, metal and glass. Of these materials, the exterior of the glass bottles had the least amount of germs, while metal had the most germs. The hard and soft plastic bottles were about the same amount, halfway between glass and metal. Glass bottles may carry the least amount of germs because glass is less porous than plastic and metal. It’s also easier to see if the inside is dirty.

cleaning method

Respondents were asked how often they clean their water bottle: never, rinse only, wash only, or rinse and wash. Those who reported never cleaning their bottles and only rinsing had higher levels of bacteria than those who washed and rinsed their bottles.

refill frequency

The results showed that the bottles that were refilled frequently throughout the day had more contamination than those that were not refilled as often. This may be because a bottle requires more frequent touching when refilling, and the water may run or drip down the sides, creating a wet source for more bacteria.

beverage type

The study asked its participants what the water bottle contained over the past seven days. Of the 90 water bottles, 72 contained only water, but 16 contained other beverages (coffee, tea, juice, sports drinks, or soda). The bottles containing beverages other than water were significantly more germ-rich than the bottles used only for water.

How to properly clean your drinking bottle

It is evident that there is a clear link between an unwashed water bottle and the growth of bacteria. Here’s how to keep you and your family healthy by cleaning your water bottles.

It is recommended that you wash your water bottle daily or at least every few days. Be sure to clean not only the inside but also the outside.

If you can put your water bottle in the dishwasher, great! Most reusable metal and glass water bottles are dishwasher safe. Place on the top rack, making sure to remove the cap. You may need to wash the straw separately with a straw brush.

If you can’t put it in the dishwasher, don’t panic. There is a safe way to hand wash these water bottles.

what you will need

• Liquid dish soap
• A bottle brush
• A straw brush
• A paper towel or a clean and dry tea towel

Fill your water bottle with warm water and some liquid soap. Scrub the inside and lid with a clean bottle brush (or one small enough to fit inside). Rinse and repeat. Also clean the outside of the bottle. Always dry the bottle completely after cleaning. If your bottle comes with a reusable straw, consider purchasing a straw brush to clean the inside.

bottom line

After completing this article, clean up your reusable water bottle—especially if you haven’t done so in the past week. You may just be carrying around harmful bacteria in your metal, glass, or plastic water bottle.

However, I am in no way suggesting that you should turn to single-use plastic water bottles or bottled water. We want to protect the environment just like you do. But for your own health, you should wash your water bottle every other day, if not every day. Don’t share your water bottle with others and wash it out especially when you’re sick. If you refill it frequently throughout the day, dry off excess water on the outside. Use warm water, soap and a bottle brush to wash. Your immune system will thank you.

The information contained in this article is for educational and informational purposes only and is not intended as health or medical advice. Always consult a physician or other qualified healthcare provider with any questions about a medical condition or health goals.