To each his own. I've got both horizontal and vertical nipples on 5 gallon buckets out back, and they are in the sun, and they are working fine, and are checked and filled daily. Temperature is always fine, even on 90 degree days at mid day and in the after noon-trust me, I'm a worry wort, I check. Letting water run out and not refilling is a great way to kill just about anything. That's probably what did it alone. Poultry nipples aren't inherently bad. There are many ways to water birds and I for one like the reduced chicken wormload that comes from only drinking pristine water and the dry, less stinky pen that comes from decreasing water waste, but like I said, to each his own.