How Often Should You Clean Your Water Bottle?

I own at least 10 reusable water bottles, but I can never find one when I need one. They wind up in various backpacks, my gym bag, the back seat of the car. So when I am able to find one, usually on my way out the door, and grab it, my kids are like a Greek chorus advising me against it. "Ugh, Mom, no! Gross! At least clean it out first!"

Shockingly in this instance, my offspring are more sanitary than I am. I consider it a minor miracle if I even make it to the gym, so if I discover my water bottle in my gym bag and it doesn't smell musty... how bad can it be?

Pretty bad, actually. My long-suffering water bottles are in actuality bacterial petri dishes that, ideally, should be cleaned every day. So says Ken Medina, sales associate at Uncle Dan's Outdoor Store, which sells a variety of camping and outdoors supplies, including water bottles. He said: "We say you should clean them out like every day, to make sure there's no bacteria in it." Medina notes that the cleaning depends on what kind of water bottle you get; some with tiny pull-out straws can get very dirty and hard to clean: "There might be parts where you really can't get in there."

If you're not satisfied with your usual bottle brush or sanitizing in the dishwasher, places like Uncle Dan's also offer specific water-bottle cleaning kits. But, Medina says, "Either way you should always be cleaning them out. The outside and then the inside." Then he brings up something I hadn't considered before: "I recommend washing the outside because there's always bacteria around. You grab the bottle around with your hands, and that's like the second-dirtiest part of your body." It caused me to kick myself internally over being so lax about my bottle cleaning.

Even with all that bacterial activity, though, Erica Smith, former research faculty at Northwestern with 20 years of biomedical research experience, and a Ph.D. in biochemistry and molecular biology, only cleans her bottles about once a week. She says that she has two separate concerns when it comes to water bottles: "One is the build up of bacteria in between washes, particularly around the part that makes contact with your mouth," which is its own bacterial haven. "If it starts to have kind of a slimy texture to it, definitely time to wash."

The second concern involves what the bottle is made of, because of the difference in the leaching of chemicals. Smith says, "If your water bottle is made of stainless steel or glass, it's probably safe to drink from it if the water has been in there for days to weeks. If it's made of plastic, even BPA-free, I prefer to dump and refill. Just out of an abundance of caution."

There's another reason to clean out your water bottle more often: taste. I find water gets "stale" if it sits around, making fresh cold water much more of an elixir that might actually get me through kickboxing class. Maybe it's psychological, but I notice a discernible difference. So rinsing and cleaning out a bottle not only makes the water safer to drink, but—to my mind—makes it taste better. Guess that makes more frequent water-bottle-cleaning a win-win, even if it does add a few minutes to my harried gym schedule.