On the Ciao Ciao theres an inner pocket that kinda fills in the top. Its just a flap by any other means if u open it the things would fall to the bottom, unless its in the inner zipper pocket. The Ciao doesnt have that inner pocket though.. Did that help?
I think a water bottle might be a bit bulky for the Ciao. I use with the second set of rings (making it longer 7" x 10") and I can easily fit a denaro wallet, iphone, keys, and other misc purse junk inside.