Watering Cows with a solar waterer

We don't keep our cows up in our yard for the winter as exercise makes for healthier cows. The problem with this is they need water when they are out in the field. We solved this problem some 10 or 15 years ago by building a solar water that works all year round. Our local county had a field tour to some other farms in the area. One of these farms had a system similar to this ours. We took these ideas and build our own system. Back then there was hardly any of these systems around and the commercial systems were few and far between and not yet very refined. This system will water cows at 40 below with no problem, and has been very reliable, although when we first built it we had to get all the kinks out of it. So far we have only had it give trouble once this year when the switch on the door became misaligned. Some years during the shortest days of the year we run short of power because of cloudy days, but this year has been very good.
The system consists of an old kitchen sink mounted on top of a 24" culvert standing vertical in about 3 1/2 meters of ground, down below frost level. The culvert is insulated with Styrofoam to keep the water reservoir in the bottom from freezing. The water comes from a dugout located about 7 meters away. The reservoir is kept full by a horizontal pipe buried below the frost line from the dug-out to the culvert.
For the cows to drink they push their nose on the door above the sink which in turn moves a switch that turns on a small pump located in the bottom of the culvert. The water is then pumped up to the drain in the sink where the cowthen drinks to her hearts content. When she is finished drinking she backs away from the sink, the door falls closed, moving the switch which shuts off the pump. When the pumps shuts off, the water then drains from the sink back below the frost line in the same pipe it came up.
With a system such as this we are able to completely fence our dug-outs to keeps the cows out which allows for a healthy riparian area for the wild animals and birds. A healthy riparian area keeps the water quality much better.