You do pay for bottled water. I bring a few bottles of bottle water and refill them with the water from the Buffet area when I run out of bottled water.
In 1991 I brought in 3 cases of diet soft drinks. They threw the suitcase (soft sided) and on impact several of the cans got holes in them and leaked. Today I bring in the twelve packs, they seem to carry better. Luckily, my soft drink consumption has been reduced greatly and all I need is one or two a day.
Since we will be driving to Florida for our next cruise, I plan on packing a couple twelve packs and that will be more than enough soft drinks for 3 adults for 7 nights.