Water backpack

[Unofficial627]

I'm not exactly sure of what it is called, but there are these backpacks that have a pouch inside that you can put water in. It seems good for biking and sports where you are moving constantly. I thought, why not at Disney? But are these things allowed in? They are like a backpack so I thought you could, but still, I'm not sure. Thanks!
P.S. I think it's called the Camelback or something like that.