Hi Robert,
Welcome back to the Disney Parks Moms Panel! Thank you for bringing this question to us!
We always see lots of resort guests filling their refillable mugs at water fountains in the parks. We have used our mugs at water fountains in the parks but when we tried to use them, the lids would come off at times and leak water. Occasionally, we have used some of our dining plan snack credits to get bottles of water then we just refill those during our visit. Or, we bring water bottles for the girls and my husband and I just get free cups of ice water from various places in the parks. Water bottles take up a lot of backpack space, so we try to conserve space by not bringing four large water bottles in the parks.
Just keep in mind that you can get free cups of ice water from various places in the parks (generally, any place that sells fountain drinks). On our most recent visit, the cups were rather small though, so we typically got two per person. When we stay in a villa or suite that has a full-size refrigerator, we also freeze water bottles at night and take those into the parks. Since we typically go in late spring or summer, the frozen water bottle starts to melt once we hit the heat in the parks but the bottle keeps some ice for a good portion of the day. If you are carrying your water bottles in a backpack, I also suggest that you use a backpack with a side compartment for the water bottle. Even with lids that close tightly, sometimes the lids come undone and we have found ourselves dumping water out of a backpack.
Robert, if you want to take a break from drinking water, try the
Flavors of Club Cool in Epcot. For free, you can sample Coca-Cola flavors from around the world. On our last visit, my favorite was the raspberry flavor from Zimbabwe!
Magic, memories and Minnie Mouse hugs,
Donyell