Man, I have to agree with North Force, My well goes into a giant underground lake, millions of gallons of water. It seems to me even a small well that is in the rocks that only produces 3 or 4 gallons a minute, still better to treat water after drawn. Unless your problem is a dead animal, or feces in the casing itself. I'd treat the water after you pump it. If your problem is the later, then you'll have to treat it in ground. Maybe your well are different then mine. I can treat a problem in the casing, but would be wasting my time trying to treat the aquifer.