Unfortunately the cows are on neighboring property so moving them isn't possible. This property does have horses so it is possible to keep them away, though there is very little manure around the well. It probably doesn't take much. If the neighbor will test their well and it is positive then it...
I agree it is unacceptable which is why a solution is being sought. A typical well in the area is 1 to 2 gpm. This one along with the neighbor's is about 13 gpm. To get a well where bacteria would not be a risk would need to be over 100feet. There probably isn't water here even at that depth...
A system already exists with a tank to reduce nitrates, a tank with calcite and a water softener. The UV would be at the end before it goes to the house. The system has had chlorine added previously but the bacteria comes back. The well is only 20 feet and there are cows all around so it will...