Hi there, Michelle!
Thanks so much for stopping by the Disney Parks Moms Panel. I'd love to help you plan the final details of your Disneyland Resort vacation!
As a Guest who almost always brings a backpack into the parks, I'm happy to let you know you can always take your backpack with you on attractions. Typically I have put mine at my feet. I also often
rent a locker for the day in the parks. For one low cost you get a locker that you can access as often as you'd like throughout the day. This is priceless when we want to stow extra clothes, jackets, souvenirs, or snacks we may not need all day. You can find locker rental locations in each park as well as in the esplanade between the parks.
I'm happy to let you know that you can also always bring a refillable water bottle into the parks. I never leave without mine since staying hydrated is so important when walking in the sun all day. You can get complimentary ice water cups at all Quick Service locations in the parks to fill your bottle, and there are also
filtered water bottle stations in Tomorrowland and Star Wars: Galaxy's Edge of Disneyland Park as well as standard drinking fountains located throughout the parks.
I hope this helps, and please feel free to return if you have any other questions while planning your magical vacation!
-Jennifer