How often should you wash your water bottle?

Do you use your reusable water bottle multiple days in a row without washing it? Do you wash it and then refill it before it dries completely?

Both habits can lead to bacterial growth and illness.

A study published in Food Protection Trends looked at the germs in 90 reusable bottles and found that coliform bacteria like E. coli, which can cause stomach illness, was among the most common.

The 2017 study showed that saliva backwash in your water bottle leads to bacteria breeding, especially if you keep your water bottle at room temperature all day or use an opaque bottle, as dark and moist environments are breeding grounds for bacterial growth. The study pointed out that while consumers may realize the importance of cleaning food-contact surfaces, they don’t realize that it’s just as important to thoroughly clean water bottles. Besides E.Coli, other common foodborne organisms associated with unclean water consumption include Salmonella and Campylobacter.

“At a minimum you should pour out water from your reusable water bottles at the end of each day to eliminate some germs,” says Dr. Robert Citronberg, an infectious disease specialist at Advocate Lutheran General Hospital in Park Ridge, Illinois.

“However, to get rid of the bulk of the bacteria and decrease your likelihood of getting a stomach bug, you should scrub the entire bottle, inside and outside, including the lid and straw, and let it air dry completely after you finish each time,” says Dr. Citronberg. “The use of a bottle brush for these popular tall bottles that have the thin necks is key, and I recommend using dish soap or better yet, a bleach-based cleaning product labeled safe for drinkware.”