Why do you put bleach in their water???
Correct, you are not supposed to use ACV in the galvanized waterers.
Stainless steel is non-reactive, so I think it would be fine to use ACV in stainless steel.
My flock has been raised exclusively on organic feed & pasture, never vaccinated or given any medications. Their waterers are the only thing they come in contact with that make me unsure of the health implications....
I've seen some glass & ceramic waterers, but they are always very small. With an average of at least 30 chickens, I need something of good size.