That is such a misleading topic when you mind is not... exactly on chickens. Anyways, I was wondering if anyone had tried doing double buckets with foam insulator? One large bucket, one slightly smaller bucket inside (so there is an inch or so of space between) then running small PVC pipes out to the outer bucket to feed nipples then filling the gap with foam insulation (the liquid epoxyesque type that you inject then it expands into foam)? I imagine, especially if you fill it with warm water, it would stay unfrozen until you next needed to fill it... unless I am over engineering the issue? Could also work in summer with ice too.... add ice for the chickens to have a cool water source..