Not meaning to hijack the thread, but I'm contemplating changing to horizontal nipples as well. However, my "Big Girls"--6 year old BA's---take big, long drinks, esp. in summer. I believe that when their wattles get wet in their traditional waterer (plastic jug/red tray beneath), it helps cool them in our VERY hot summers. For that reason, I'm reluctant to make the switch over, although I feel a horizontal nipple waterer would have many benefits in my situation.
Having said that, when we get rain or dew drops on the pipe fence at the barn, my girls love to "drink" the drops that hang underneath. Maybe the vertical nipples would deliver more water.
Anyone care to comment on water volume between vert and horizontal nipples?