Spent the morning getting water to 160 outdoor pigs.
The drinkers that have faired the best are the 14 litre metal ones that have been sunk in to the mud by pigs, nicely insulated they've mostly stayed liquid if not actually running. Next after those are the 120 litre cow/horse drinkers, plastic combined with bigger capacity has proved quite useful in this weather.
The worst are the 2.5 litre ones above ground, freeze solid too easily and even for 2-3 micro-pigs just not enough capacity when filled by hand. These really need to be indoor only i think, won't buy any more.
Will definitely by buying more of the big plastic drinkers and sinking them further into their concrete pads