There's a hole/lip in the base like a normal waterbottle hole.
But, there's two holes in the top of the lid (very small, like wire size) which you are presumably supposed to put wire through to attach the waterbottle, but this is on the side that the lid hinges
This means that if you were to use this the waterbottle would be at the back which I think's a bit stupid.
Another option to attach it are the suckers that come with a mini duna (what I use) suckers and some string, velcro, or a stand alone water bottle holder