You should clean your reusable water bottle after every use, ideally after finishing the entire bottle. If you refill and use the same bottle multiple times throughout the day, washing it twice a day—once in the morning and once at night—is recommended

. In addition to daily cleaning with soap and hot water, sanitizing your bottle at least once a week or every other week is advised to kill microorganisms that regular cleaning might miss. Sanitizing can be done using diluted bleach or hydrogen peroxide

. You should clean your bottle more frequently if:

• You use it during daily workouts
• You are sick, to avoid reinfection
• You drink beverages other than water, such as juices or protein shakes, which promote microbial growth

Experts also emphasize thoroughly cleaning all parts of the bottle, including lids, straws, and nozzles, and letting them dry completely upside down before reuse

. In summary:

• After every use (or twice daily if refilling repeatedly)
• Sanitize weekly or biweekly
• More often if using for sugary drinks, during illness, or workouts

This routine helps prevent bacterial buildup, mold, and unpleasant odors, keeping your water bottle safe and hygienic