If you leave an open water bottle in the fridge, a few things may happen depending on the conditions and the length of time it remains open:
Absorption of odors: The water in the bottle may absorb odors from other foods or substances in the fridge. This can result in the water having a strange or off-putting taste.
Loss of carbonation (if applicable): If the water is carbonated, leaving it open in the fridge can cause it to lose its fizziness over time.
Contamination: An open water bottle in the fridge may be exposed to airborne contaminants or potential splashes from other food items, which could compromise its cleanliness.
Change in temperature: While the fridge will help maintain a relatively cool temperature, the water may not stay as cold as you'd like since the fridge is not perfectly sealed and its temperature may fluctuate.
Evaporation: Over an extended period, some of the water in the bottle may evaporate, especially if the bottle is not tightly sealed.
In general, it's best to keep water bottles tightly sealed to maintain their freshness and cleanliness. If you plan to store water in the fridge for a longer period, consider using a container with a secure lid to avoid potential issues. If you notice any changes in the taste, appearance, or odor of the water, it's best to discard it and refill with fresh water.