Last summer we installed an old sink outside so that it was easy for visitors to wash their hands after handling the alpacas.
Its not going to win any design awards but to warm the water we simply routed the water pipe over the East facing stable roof. Initially we used black hose pipe but in the summer months the water became much too hot. So now we use a pale green pipe which absorbs less heat and warms the water very well.
Of course this is useless in winter but then we get far fewer visitors in winter and we don't tend to hang around outside for very long when we do!
Adrian Stewart