|St. Mary of the Spring - Istanbul|
Because holy wells exist in so many cultures, in so many religions, in so many locations and in so many time periods, most believe the concept is essentially intrinsic to man - more or less a fundamental human instinct to hold such sources of water reverent. Being how water is right behind air in terms of human survival, is it any wonder?
Holy wells have been known for a long time, and people who study them claim their use and special care go all the way back to the Paleolithic era of very early man. This post was just to introduce you to the term. There is a more complete rendering on the topic here - at least as far as European holy wells go. This link also has a number of sources where additional materials are listed.
Oh, and about Nympaions and Haeligewilles? These are terms for the same thing in different languages/cultures. You can find out more on this entire subject at the Wikipedia site linked above. Enjoy. It's 2012. Do you know where your Holy Well is?