There clearly must be more to this than those on the outside can appreciate but having met some of the balpa reps they do not seem a reactionary lot who would take action on a trivial affair. The issue of the water restriction by the company seems daft given the restrictions on an individual getting their own onboard. I would say you should drink one of those 500ml bottles per stretch to avoid problems with dehydration. If the crews already took a hit on pay to preserve access to other drinks then surely that should be honoured. Don't know about the contract captains issue so can't comment.
One slightly off-thread comment though related:-
long time non members of the union are rejoining
And then they will leave again when it's all over but still benefit from others hard work. Leeches, I wouldn't let them back in temporarily if I had my way (which of course I don't!)