When the topographer Samuel Lewis noted their existence in 1837, the local interpretation was that they had served as an ancient reservoir, which is an unusual purpose to assign to what archaeologists would now likely classify as a souterrain, an underground stone-built passage or chamber used in early medieval Ireland variously for storage, refuge, or both. The precise location of what Lewis described has never been entirely settled, and that uncertainty is itself part of what makes this site quietly interesting.

Lewis placed the discovery in the vicinity of Ballintaggart burial ground, and the first edition of the Ordnance Survey map marked a 'cave' in the nearby Lough townland accordingly. When surveyors went to investigate, however, they found it already closed up and had to rely on local information to connect it with Lewis's account. The situation is further complicated by a second candidate, roughly three-quarters of a mile to the north-east, in a field in Ballintaggart townland known locally as 'the well field'. There, an underground drystone-built chamber, roofed with large flat flags and accessed by stone steps, survives in a partly flooded condition, its floor filled with loose stones. Whether this is the structure Lewis encountered, or whether both sites once existed independently, remains unresolved. The possibility that Lough townland held its own souterrain, distinct from the Ballintaggart well, cannot be ruled out.