Hi there, Kristen!
Welcome to the Disney Parks Moms Panel! We're glad you stopped by with your question!
I'm pleased to tell you that Guests can bring water bottles and
food items that do not require heating into the theme parks. Alcoholic beverages and glass containers (with the exception of small ones such as baby food jars) may not be brought into the parks. I've previously taken snacks and water bottles into the Disney theme parks and both water parks and have never encountered any issues when doing so. If you're hoping to refill your water bottles during the day, you can ask for a complimentary cup of ice water at any Quick-Service dining location or snack cart selling fountain drinks.
Great news, Kristen.
Backpacks and coolers are also allowed in the theme parks, but they cannot be larger than 24" long x 15" wide x 18" high. I love bringing a crossbody bag or a medium-sized backpack into the theme parks with me, so that I have all of my park touring essentials at my fingertips. I also take my bag onto the attractions with me.
Lockers are available to rent in all four theme parks and both water parks if you prefer to not carry your items throughout the day.
I hope this information is helpful with your vacation planning, Kristen! Please let us know if you have any new questions. We would love to assist you further in planning a magical trip!
~Jodie