You are quite right Goff, actually the cottages in the local villages had numerous wells shared between them, and it is a fair enough question whether their water is clean or not. From what I recall it is a matter of depth and time the water is in the chalk prior to resurfacing, although it is obvious that the deeper it penetrates the longer it will be in there presumably it is also the amount of sheep present as it is their poo that is a common source of cryptosporidium. Wells in Overton and Lockeridge and Manton were puddled lined so the water enters from the bottom.

VBB