The site now marked as Saint Dermot's Well on the shore of Lough Derravaragh in County Westmeath turns out not to be the original location at all. What is there today amounts to a concrete pump-house and a spring, with no visible traces of the older devotional site that once gave the well its name and significance.

The discrepancy becomes clear when the 1837 Ordnance Survey six-inch map is compared with later editions. On that earlier map, Saint Dermot's Well is plotted some 270 metres to the north-east of where it appears on subsequent OS editions, and roughly 255 metres from the original shoreline of Lough Derravaragh. The 1837 map also shows a separate, unnamed well sitting directly on the lake's edge. At some point between the first survey and later revisions, that unnamed lakeside well absorbed the dedication, and the name of Saint Dermot migrated with it, leaving the true location effectively forgotten. The original site shows no surface remains whatsoever in aerial photography. The well's patron is Diarmuid, son of Lughna, identified as the patron saint of the parish of Faughalstown; holy wells of this kind were typically sites of local veneration, sometimes visited on a patron's feast day for prayer or ritual rounds known as "patterns". How and why the cartographic reassignment happened is not recorded, but the consequence is that the place now bearing the saint's name is almost certainly not the place where that name belonged.