PET plastic isn't necessarily gas proof long term but it would take some external lack pressure to suck air out - I go with pressure or temperature changes over time.
Select as Best AnswerUndo Best Answer
http://www.bettix.co.uk/plastics-fluorination/why-fluorination-the-problem -Here's the only solution to stop the paneling of bottles, get your bottle fluorinated.
Here's the answer: It's called panel sink?.........what? why that name? Oh well, here is what I found.
I am wanting to know the answer to the same question. I believe this experience of collapsed unopened water bottles is a little more detailed than we are told. Does the plastic degrade? Lots of people probably have cases of water that have had this experience after storing for a few years.
Is it dangerous to consume?
Has it been moved to a lower altitude?
Because leaving water in a plastic bottle for years just SUCKS! Don't do it.
Lots of reasons, I think most likely is nacho's suggestion that the bottle is permeable and lets some gas out.Gasses dissolve in the liquid, thus acting as a liquid and not exerting their pressure on the bottle walls.The plastic in the bottle could be actively 'eating' the gasses - I have no grounds to support this theory, but given that some plastics off-gas, it makes sense they might react with and store some gasses.
. Could be that some germs have used up all the Oxygen, Nitrogen, &c. . Maybe plastic bottle are ever so slightly gas permeable and the gas gets pumped out with temperature fluctuations and/or variations in pressure. . Magic!