I bought a water package from RC. Sure it was expensive, but it was convenient for my (and my traveling's party of 4) needs. It was sitting there in my stateroom once I got onboard.
We bought the lowest # of water bottles (8 large bottles, or roughly 16 regular sized bottle water, or roughly $2.5/regular sized bottle). You could buy it from the fridge if you need fewer. We finished all of it through our 3-day cruise. I tend to drink a lot of water normally anyway, so that was no problem. We had two port days and we planned to be out and about (booked a few excursions) and it was convenient to carry about smaller water bottles with us (especially on hot days). We also ended up buying another 2 bottles of water(at $1 each) at one of the ports because we finished the ones we carried and it was super hot out.
You could just bring an empty bottle and fill it up on the ship. That's just as easy. But since I'm trying to drink less soda and wanted the convenience, the package makes sense to me. I won't lie, it's definitely a bit on the expensive side (I was on the fence when trying to decide whether to buy it or not), but it was definitely convenient.