The ship's tap water is distilled on board and is better than any bottle water you could bring with you ... purer.
You can bring soda pop - no restrictions. Princess (and most other lines) will sell you a soda card which is good for any of the tap soda at the bars (not cans).
You can bring wine for drinking in your cabin ... if you bring it to the dining room, they'll charge you to uncork it something like $15! No charge to drink in your cabin, but bring a cork screw.