How long do the bonds in a molecule hold under nominally stable conditions? Disclaimer: I am not a chemist

I was just drinking my Ice Age mineral water which is 'untouched since the Ice Age' and wondered if the bonds formed in each molecule have remained intact for all those years.

In a liquid that is just lying there underground I'm guessing that there is some, if not very energetic, movement of the molecules. What happens when they bump into each other? Might an atom become dislodged and bind with another molecule?

I have no idea but the thought interested me.
Water with its fluctuating hydrogen bond networks is a special case. If you feel for it, have a look at Water clusters: Untangling the mysteries of the liquid, one molecule at a time, but it doesn't answer your question ;-)

It is more interesting to have a look at paleochemical/geobiological findings.


A complex organic molecule, such as 2$\alpha$-methylhopane was isolated from 


  2700-million-year-old shales from the Pilbara Craton, Australia
  (Source)


Have look at the website of Roger Summons at MIT and his freely available publications, such as The Exceptional Preservation of Interesting and Informative Biomolecules.

In short, bonds can last a pretty long time!