Hi Kate,
Absolutely! You are welcome to bring water bottles, juice boxes, soft drinks and snacks into the parks with you. I've even seen families bring entire meals! Just last month, I sat near a large family that unpacked a complete hot meal with rice and vegetables at picnic tables near the Germany pavilion at Epcot.
There are a couple of caveats: You can't bring glass containers (except for baby food) or outside alcoholic beverages. And if you bring a cooler, it needs to be smaller than 24"x15"x18". You can find the full list of
restricted personal items here.
I don't recommend weighing yourself down. Unless you have a stroller with a storage basket to hold the cooler, I would pack lighter snacks and water bottles that can be carried easily in a backpack or tote. I often toss granola bars or packets of trail mix in my bag for a protein boost.
Staying hydrated is so important at
Walt Disney World, especially in the summer. You will find water fountains scattered throughout the parks for refilling your personal water bottles. And every counter service restaurant will give you a free cup of ice water that you can use to fill your bottles as well.
Even in table service restaurants, I often ask for an ice water to go when our meal is over. It's impossible to get too much water.
Thanks for stopping by the Disney Parks Moms Panel, Kate. Please let us know if you have any more questions as you plan your late summer vacation. Enjoy!
Wilma