Greetings Laura,
I'm thrilled to know you'll be visiting the
Disneyland Resort!
Guests are more than welcome to bring their own water bottles into the Parks.
If you take a reusable water bottle or a hydration backpack, which is what I recommend, there are many water fountains throughout the resort for you to refill.
You can also request a cup of ice water free of charge at any
dining location.
As far as the cooler, you are free to bring your own as long as it's not larger than six-pack sized.
Snacks are always a part of our routine when we visit the Happiest Place on Earth!
Since I have two young boys, I always make sure to pack items like: pretzels, fruit bars, carrot sticks, raisins and string cheese. I do this in case they start getting hungry while we're waiting in line for an attraction.
You should have no problem doing the same!
I will mention though that most quick-service dining locations offer a Kids' Power Pack agreeable to any budget.
The pack comes with yogurt, apples, carrots, banana, crackers and your choice of water or milk!
I hope you find this helpful.
Thanks for visiting the Disney Parks Moms Panel!
Have a Magical vacation!
-Anabel M.