My dad worked for a company that had the contract to import Perrier.
Seems that they controlled everything, from the well, to the filtration, to the sand that made the bottles, to the bottling plant.
Seems that the bottling plant had a filtration system that was contaminated by a few molecules of benzene.
So they shut it down.
It took them 6 months to rework it, clean it out, and bring it back online.
We knew about this shit 30 years ago.