To keep your reusable water bottle free of bacterial odors, it's advised to sanitize it once a week. You can easily do this with a common ingredient in your pantry: baking soda.
Start by emptying your bottle and giving it a quick rinse. Next, add two tablespoons of baking soda to the bottle, fill it with warm water up to the top, and let it sit overnight.
While you sleep, the baking soda will deodorize and clean your bottle. In the morning, wash the bottle as usual with soap and water and check if the odor has been entirely removed.