how long does water stay OK in a plastic bottle?

How long does water stay OK in a plastic
bottle? Here [1] it says 2-3 hours!

Does it really happen that fast? And what is it
that deteriorates?

Will the movement of the bike preserve the
freshness for additional time?

I just bought two bottle holders from French
Zéfal and installed them. I noticed when you do
not have a bottle in them, the plastic arms are
too close so they hit each other and make an
annoying sound. But just cutting off a small
part of one of the arms and it is fine.

The bottles are also from Zéfal. 650ml, BPA
free. Seems good.

[1] https://www.quora.com/For-how-long-s...lastic-bottles

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