Where do you live? How cold are the winters? I prefer the horizontal nipples over all the kinds I've tried. (Don't use them for waterfowl, though. They need to submerge their heads.) If you keep a bucket deicer in your water bucket, the horizontal nipples don't freeze. You do need to keep on top of the water levels though, because the deicer will burn out if it's not submerged in freezing temps.
This is how they work: They're controlled by the temperature of their surroundings and cooled by water. They have no mechanism to turn them off if the water level drops too low. As long as the air temp is above freezing, they'll be okay, but if the temp is below freezing, they will turn on and quickly overheat and burn out unless they're under water.
The whole point of using water nipples on a bucket is to keep the water clean, so you really need a lid, which makes it easy to let the water level drop.
I just give my birds a bucket full of water with a heater (er... I mean deicer--different things) in it. As for using PVC pipe with nipples, you'd need a deicer or heater and a recirculating pump--too much for me to figure out and not really worth it to use nipples. Some folks use them in summer only, as for quail cages--where it might be worth the trouble.