What appears to be a modest feature of the Dublin uplands is in fact the remnant of a devotional site that has quietly shed its original identity over the centuries, its old dedication dissolved into a more familiar name through nothing more than the drift of spoken sound.

The well was originally dedicated to St Santán, the saint associated with the nearby early ecclesiastical site of Kilmasantan, whose ruined church sits roughly 175 metres to the south-west. Writing in 1876, the antiquarian Shearman noted that both the church ruins and St Sanctan's Well were still identifiable in Glenasmole, but observed that the old name had been reshaped, as he put it, by "a very facile adaptation of sound" into Kill St. Anne, effectively reassigning the site to a quite different saint. The process is a familiar one in Irish placename history, where Gaelic names eroded gradually under anglicisation until they settled into something phonetically similar but historically unrelated. By the time Ó Danachair documented holy wells across Ireland in 1958, this one had already ceased to be an active site of veneration, a status confirmed again in Healy's 1975 survey of the area.

The well sits on the Glassamucky Brakes section of the Dublin Mountains, above the Glenasmole reservoir and north of the remains of St Anne's Church, which itself retains the corrupted placename that displaced St Santán's memory. The well's physical dimensions are modest, roughly 1.22 metres long, 0.92 metres wide, and 0.3 metres deep, and the ash tree beside it serves as the main visual marker. Photographs taken by Patrick Healy in 1988, now held in the South Dublin Libraries Local Studies Collection and accessible through their digital archive, give a sense of how the site appeared before the turn of the century. The ground can be soft on the approach, particularly after rain, and the landscape is open upland rather than managed path.