Soft drinks are included in all sit down meals. In between times they are available at all of the bars, but there is a cost, plus automatic 15% gratuity. There is a drink station located aft on deck nine. Last year that station included milk, tea, coffee and water. I am inferring from recent posts that they have added juice and or lemonade to this station.
We are not planning on buying the mugs, too much trouble to keep them with us. Also, soft drinks at meals are pleanty. My kids are very happy with the offerings at the drink station.
I don't recall if they even have bottled water for sale, but the water from the drink station is apparently filtered and tastes fine. I'm pretty particular about the taste of my water and never had a problem. Bring or purchase a couple of sports bottles, you can fill them with ice and water at the drink station.
Happy sailing!