Exactly, I have mine drilled in the bottom of the bottle and I can refill it just by taking off the lid. (Leave the spout open to keep it from creating a vacuum seal)
Although, I ruined one water bottle because the bottom wasn't flat enough so it leaked.
Think of a gerbil waterer. They peck at the metal nipple which pushes it up and releases a few drops of water. Mine have never dripped or stopped working. Its so nice to only switch out their water every couple days vs couple times a day!
I had little holes in the top of my dog crate/ brooder that I could use wire and wrap it around the water bottle to secure it. Once I move them to the larger wire dog crate brooder I will wrap the wire around the wire corners. Not sure how to do it with a cardboard brooder, maybe of strong...
Haha, my first attempt was with a pearing knife and cut awkward square holes that may have hurt the baby chicks from the rough edges. It's been working out great so far.
Here is my zero waste feed and water setup. Just like Kathleen's my chicks could fit in the holes when I first brought them home. Added some doubled over duct tape as a temp boarder and we were good to go! No gravity feeder element just full so the can eat and since its so big (holes around 75%...