Over at His Grace The Hermeneuticalness, The Owl of the Remove asks Fr. Finigan for the formula for blessing a well.
This brought back memories of my childhood in Ireland where there are many, even thousands of Holy Wells. I don't know how common this is, or was, in the U.K. but I think it was essentially a Celtic practice. My recollection is that a well would be considered special to a particular saint, usually a very early one, often local and sometimes the one who is credited with having brought Christianity to the area. This was a very strong belief in country places. The waters of the well were believed to have mystical powers to heal, often a particular part of the body or a particular illness, and access to the saint was thought to be particularly strong at the well. Near where I grew up there was is a secluded little glen with a well called Tubur na Suile, which in English means The Well of the Eyes and people with eye problems would go there to pray and bath their eyes in the water. In Celtic Christianity there are very strong ties between early saints and the landscape, with particular places having mystical properties. Many place names in their original Gaelic forms are associations between landscape features and a saint, and when translated into English mean things like Mary's Well, Patrick's Well, The Rock of this saint, The Cave of that Saint, The field of the Other Saint, etc.
Many of the wells are situated in country places, in quiet, atmospheric, out of the way corners. Sometimes there is just a simple well but often there is a stone cover of some sort to keep the water clean and sometimes a tiny stone building covers the well entirely. There is frequently a Hawthorn tree nearby, quite often overhanging the well, to which pilgrims will tie ribbons or small pieces of cloth, having prayed to the saint and drunk from the well or bathed in the water. Sometimes people leave rosaries on the tree and sometimes statues at the base of the trunk, ( though nowadays these are prone to be beheaded).
It was common for Mass to be celebrated at the well on the saint's feast day.
Veneration of Holy Wells is just one of the many observances which at one time were very strong in rural Ireland. Others included "patterns", which was the practice of visiting a site associated with a saint, eg., a well, church or abbey ruin, etc., and there preforming an elaborate series of repetitive movements and prayers while walking around the site, sometimes involving moving stones from one place to another. This seems to have died out, and is looked on today a superstition but I'm sure it had something in connection with meditative prayer and was similar to medieval use of labyrinths. It is some years since I've lived in Ireland so I'm not really sure if the practice of venerating holy wells is still strong but I have been told that because of poor agricultural practice many of the wells are now unfit for human consumption and have health warnings erected nearby.
As a footnote:I have read several times that these very strong popular traditional devotions are one of the reasons why the Irish have such an equivocal relationship with Liturgy. Very simply put they had their own devotions where they met God, privately, in the fields and at the well, and went to Mass on Sundays and Holy Days out of obligation. Therefor, though their faith was extremely strong, for most people, while they would not dream of missing Mass, the beauty of the Liturgy was not something which concerned them. Now that many of these old traditions have died out or in some cases been suppressed, Ireland is something of a Liturgical wasteland and many people I know are perfectly content with it being that way. I think I am correct in saying the, outside of Dublin, the Traditional Mass is just not making the progress that it is elsewhere, in the world. I live in a U.K. diocese with a bishop who is generally regarded as one of the least interested in traditional things, ( but not actually hostile), and yet there are within my diocese at least eight churches where the Extraordinary Form of Mass is regularly offered, and at least nine or ten more within relatively easy reach in adjoining dioceses. This in a diocese of approximately 140,000 Catholics. Yet this is more than in the whole of Ireland with a Catholic population of in excess of 3,000,000.