Is there a fine if, theoretically, one was to be foolish enough to accidentally fill a mineral water bottle with say a clear alcoholic liquor such as vodka and take it into the circuit. And get caught.
There's no question of a fine Andy.
Worst scenario is that the bottle is refused entry to the circuit. But, in practice, the check is for glass bottles or labelled alcoholic drinks.
Of course this is an entirely hypothetical situation.