VAL,
I can't remember the brand, but it was $1.50. I think they also add on the 15% gratuity which makes it about $1.75. They will let you bring your own on board if you wish. Personally, I would not bother. As reported before on the boards the water on board ship is pretty good. I used the drink station for water a lot and the only time we bought bottled water was for excursions and we usually brought most of this back to the room.
LeiLani