Hi Jessica,
I am so glad you stopped back by the Disney Parks Moms Panel with another great planning question. It is always important to be prepared, so it is great to see that you are thinking of everything. I hope our answers are and continue to be helpful during your planning process.
I am pleased to let you know that your backpack will be allowed into the parks, as long as it follows the
park rules and regulations. Please note that all bags/purses are subject to search prior to entering the theme parks as a security measure. As long as it is a pretty standard size, you will have no problem stowing the backpack at your feet or in front of you in the ride vehicles as you visit all the attractions. However, if you decide that you would rather not carry it, there are
lockers available to rent at all four theme parks. It is my personal recommendation, though, to forgo the lockers as they are toward the main entrances and having to go back and forth for things could waste valuable enjoyment time. We always have at least one backpack stocked with water bottles, small packaged snacks for in between meals, sunscreen, and jackets. One other very important item that I always take and fold up in one of the pockets is a large plastic trash bag. We use this to put our backpack in when we ride water attractions to keep in dry. Then, once we have exited the ride, we shake it out, turn it inside out, and refold and stow it away again.
As I stated earlier, you will be allowed to bring in water bottles, as long as they are not in glass containers. You can also bring in necessary medications, however, they do also sell over the counter pain relievers at some of the retail locations.
I wish you a magical visit, it will be here before you can say "supercalifragilisticexpialidocious!"
~Allison L