Many of the Irish wells have folklore attached to them that the associated saint walked along, banged the ground with his crozier and the water gushed forth.

This is one: http://www.megalithomania.com/show/site/516

[this well is a few hundred metres away and appears to be a megalithic tomb: http://www.megalithomania.com/show/site/519 ]

Several Irish tombs are built on springs, Newgrange being one! There is also Shalwy in Mayo and Church Mountain in Wicklow that 'spring' to mind. Portal tombs are always near to water, usually small streams, and is such a constant in their immediate landscape that it must have meant something to the builders. The life giving source of these waters must have been special (?).

"So - the wells and springs are pretty much there cos they've always been there? No sudden happenings of springs suddenly gushing forth?"

I was pondering this after experiencing some rather odd water tables out in the hills last week. Boggy bits on top of hillocks, dry bits below, where you'd expect it to be marshy. But what got me thinking was vague memories of hearing of transhumanic folk hiding water sources. If you found a water source and wanted to keep it hidden, so that it wouldn't dry up, silt up or to stop animals dying in or whatever, it would make sense to cover it, and leave some kind of marker to indicate it's presence for when you came back that way.

Then if in later centuries (millenia even?) if there were people who somehow knew the signs that indicated a covered water source, they could indulge in some theatrics, bash the cover open with a staff, and declare miraculous intervention.