A bottle sitting beneath a seat, inside a closed bag, or in a shaded area isn’t receiving the same direct sunlight as a bottle sitting next to a window.
The potential problem occurs when several things line up:
- Strong direct sunlight
- A transparent, water-filled bottle
- A bottle position that concentrates light
- A surface sitting at the focal area
Move any one of those things and the potential heating effect can change dramatically.
That’s why simply keeping bottles out of direct sunlight is such an easy precaution.
What Could the Concentrated Light Heat?
The concern isn’t really the water itself.
