Know what you mean.
I free-range most of the year and use several Tuff Stuff heavy duty rubber bowls on an elevated platform they can access, along with another typical plastic design that I use to put their probiotics or other ingredients in.
The rubber is easy to clean, the birds do not dirty the water, I can easily fill it, and it is in the shade, so keeps cool. I also use this for my ducks.
If you are looking for a coop waterer, however, I believe your birds could find a way to feceate in the bowl from above...
Good luck.
_twilia ; )