Bringing water on oasis of the seas

we see people with cases of water on every other cruise line, is this not allowed on Royal Carribean?

The better place for your research is the RCI board, here:

https://boards.cruisecritic.com/forumdisplay.php?f=83

If they don't allow it, that is up to them.

Realistically there is no reason to bring a case of water on board. The water on board is as pure as any bottled water, tastes great, is free, and doesn't come with a plastic waste problem.

Sometimes, they will allow it....other times, they won't. Their printed "rules" say NO beverages. None. CruiserBruce is correct. The ship's water is the same stuff that's in those plastic bottles...but without the plastic fallout. It's perfectly fine, plentiful and included in your fare! Your food, Ice and beverages are all made with ship's water. Better than what you probably have at home.

No matter what you do I would bring a bottle so that you can use the ships water and use it in port. As mentioned the ships water is quite good and is used in the various restaurants.

Keith