Hi Derek,
Welcome to the Disney Parks Moms Panel! A water question - I love it!
We have taken refillable mugs into the parks. When we stopped by quick service restaurants, we asked for cups of ice water, then used those to refill our mugs or we used water fountains to refill the mugs. We now take our own water bottles with us because I have had some difficulty with the refillable mug lids twisting off and water seeping into my backpack. So, now we bring water bottles that we can re-seal more tightly.
Of course, if you don't want to drag water bottles or refillable mugs around, you can always just stop by a quick service restaurant and request complimentary ice water. The water cups are small, though, so if you go this route, I suggest that you request two cups per person. If you are staying in a suite or villa that has a full kitchen, I also suggest that you buy some bottled water. When we stayed in a two bedroom villa one year, we used the freezer to freeze our water bottles at night, then took them with us to the parks. As they melted throughout the day, we had really cold water and, the best part was that it stayed cold for most of the day!
Derek, before we travel, we always visit a Disney Store near us to pick up a few items that we need for the trip. You could also look for items at
Shop Disney Parks. This past year, our girls' godmother found the cutest Mickey Mouse water bottles for the girls at Target. They LOVED having them on our trip!
Magic, memories and Minnie Mouse hugs,
Donyell