Why does some bottled water seem to “expand” when the bottle is opened?

Question

I noticed this a while ago. I had a bottle of Evian water, and, when the bottle was sealed, the water wasn’t filled all the way to the top; there was maybe an inch or so of space between the top of the water and the cap. Then, when I opened the water, there was a “whoosh” sound, almost like when you open something vacuum sealed. Then, after the bottle was opened, the inch or so of space was gone, and the water was right at the lip of the bottle.

How could this be? Shouldn’t there be more, not less, space?

In: 16

Answer 1

Air pressure was higher inside the bottle than outside of it. The bottle deflated basically, the air at the top escaped and the whole volume of the bottle went down