Yes, it is generally safe to keep bottled water in the freezer overnight. Freezing water in a sealed bottle is unlikely to cause any harm, and the water will not become toxic or dangerous to consume.
However, there are a few things to keep in mind:
Bottle selection: Make sure to use bottles specifically designed for freezing. Some plastic bottles may not be able to withstand the expansion that occurs when water freezes, which could cause the bottle to crack or leak.
Room for expansion: Leave some extra space at the top of the bottle to allow for water expansion as it freezes. This prevents the bottle from bursting due to increased pressure.
Thawing: If you plan to drink the water, allow it to thaw at room temperature or in the refrigerator. Avoid using the microwave to thaw plastic bottles, as this can cause uneven heating and potentially release harmful chemicals from the plastic.
Ice expansion: If you freeze water in a bottle with a tightly sealed cap, be aware that the ice may expand as it freezes and could potentially push the cap off. To avoid this, you can slightly unscrew the cap or use bottles with a wider mouth that won't create a tight seal.
Freezer space: Be mindful of how much space the bottles take up in your freezer. Freezing water takes time, and it might occupy valuable freezer space that you may need for other items.
In summary, freezing bottled water overnight is generally safe, and it can be a convenient way to have cold water on hand. Just ensure you use appropriate bottles, leave room for expansion, and thaw the water properly before drinking.