Bring water bottles and refill them with water from fountains. But because you have never been to WDW, you do not know that the water tastes really bad! I would bring a container of Kool-aid or simmilar powder to mis with the water to make it taste good! (I love water, but really the water dose taste very bad!!)
Refilling water bottles is an excellent idea, we did this last time we went. Unfortunately, after filling up at MK fountains all day we had some "stomach" problems later that night. We all thought it was the water, I guess our systems just were not used to it. Anyway, someone on these boards mentioned using a brita water bottle that has a little filter in it that takes away the bad taste (and smell...yuck....) So I went to Kohl's (where they had bought one) and sure enough, they had them for only $4.99 (thanks to whoever posted that if you're reading this ) I suggest trying to find one of these also if your going to refill at the fountains. Although maybe it was just us, anyone else had problems with the water?