After using horizontal nipples since these chickens were chicks I decided to see what would happen if I gave the chickens a bowl of water. They are 15 months old. At first they wouldn't go near it. Finally the rooster took a chance and had a drink. He called the girls over. Two gave the water dish a try. The rest just didn't trust it. Later I saw some of them go back into the coop for drinks at the nipples.
Yeah, a vent is a must or the water won't flow out of the nipples. Give them time, some get it right away, others not so much. During 'training' I put down an open waterer before roost time to make sure they are hydrated going into the night hours.