This is a tough one to find! I suggest a little local help or a GPS.
It is also worth making the effort for as the site is very unspoilt. The well lies beneath the roots of a large ash tree and is almost invisible until you are right by it. Look for the small caged figurine of St. Anne and a worn sign on the tree trunk.
Underneath the tree the well is protected by an arched stone-built roof. I was expecting to see a rag-tree over the well, but there are no offerings. A mug hangs on a bush next to the well so that you can 'atek the waters', but I don't know what properties they may have.
The tree and well are situated in the NW corner of a very boggy, undulating field on a west facing slope.
This is an explanation of (and a bit of a disclaimer for) the coordinates I provide.
Where a GPS figure is given this is the master for all other coordinates. According to my Garmin these are quite accurate.
Where there is no GPS figure the 6 figure grid reference is master for the others. This may not be very accurate as it could have come from the OS maps and could have been read by eye. Consequently, all other cordinates are going to have inaccuracies.
The calculation of Longitude and Latitude uses an algorithm that is not 100% accurate. The long/lat figures are used as a basis for calculating the UTM & ITM coordinates. Consequently, UTM & ITM coordinates are slightly out.
UTM is a global coordinate system - Universal Transverse Mercator - that is at the core of the GPS system.
ITM is the new coordinate system - Irish Transverse Mercator - that is more accurate and more GPS friendly than the Irish Grid Reference system. This will be used on the next generation of Irish OS maps.