How Often Should You Clean a Reusable Water Bottle?

Needless to say, I drink a lot of water, and frequently refill it. But one day, as I unscrewed the cap and took a sip, I noticed a metallic off-flavor. Upon further inspection, I noticed there was black gunk inside the neck of my metal bottle. Not cool. I drink out of that thing!

How often should I actually be cleaning my water bottle? And what's the best way to do it? To find out, I reached out to an expert.

According to Jessica Ek, director of digital communications at the American Cleaning Institute, you should wash your water bottle after every use, especially if you and your water bottle are attached at the hip.

Why? The dark, damp interior of a water bottle is a breeding ground for germs. 

“The inside of a water bottle is the perfect damp environment for germs to spread, especially near the places that come in contact with your mouth,” she said. “A test of reusable water bottles found more than 300,000 colony-forming units per square centimeter, which is roughly the same as a pet bowl.” 

If your water bottle is dishwasher safe you could go that route, but Ek recommends using a little bit of old-fashioned elbow grease—and a bottle brush, like one of these, to get your bottle in tip top shape. Bottle brushes squeeze easily into thin bottlenecks and can reach deep into the bottle. 

Here are her simple instructions:

1. Fill the water bottle with water and dish soap. Soak the other pieces in a bowl of soapy water. 
2. Use a bottle brush to scrub the inside of the bottle, as well as the nooks and crannies of the other pieces. 
3. Rinse all the pieces and dry. Make sure the bottle is completely dry before reassembling to prevent it from becoming musty.
4. Once dry and clean, refill with water to your heart’s content (or until the next time you clean it).

Our ATK Reviews experts have reviewed many different styles of water bottles. In all of their tests, they found that the best-designed water bottles are easy to fill, open, close, carry, and clean.

Here are some tips to keep in mind:

• Bottles with fewer parts are easier to clean. The top models in our testing of glass water bottles had only two parts to deal with during cleaning: bottle and lid. We also preferred water bottles that were dishwasher-safe, which eliminated the need for a special bottle brush.
• The narrower the bottle, the more difficult to clean. Bottle brushes are great for cleaning hard-to-reach places, but some bottles were too narrow for even them to do their job.
• Built-in straws are tough to clean. In our testing of kids’ water bottles, these straws trapped bits of smoothie, even when we ran them through the dishwasher.
• Opt for water bottles with protected mouthpieces. Testers liked protected mouthpieces, which felt clean on the lips; exposed ones got dirty or dusty.