WTF Images: The Eccentric Eight

[Dartz]

Sometimes it's cross contamination from the container. Especially if it's in a plastic bottle some of the chemicals in the bottle can leach into the water.

Although there is a difference between Use By and Best Before.

Things may be fine after their 'Best Before' day - the colour or flavour or texture may go out of the factory tolerance or beyond guarantee but it'll still be edible and safe to eat. Things with a 'Use By' however, are far more absolute - they're normally either fresh or otherwise unstable in some way.