We have weaners but only over the summer, they are gone by the time its freezing. We have plastic pipe just run down the fence line on the surface, connected to drinker with a normal hosepipe protected by electric fence also run round the base of the pen.
As we are on our own water supply I don’t leave it on, we have a big drinker and just turn it on once a day to fill it up. It never gets less than half full.