The pump house is unpromising architecture, but the water inside it carries a longer story than its casing suggests.

In the seventeenth century, the Franciscan friar and hagiographer John Colgan documented a cluster of holy wells in this part of Westmeath, recording that three fountains existed whose waters, joining together miraculously, turned a neighbouring mill. Colgan named each well by its dedication: one to St. Aedh, one to St. Brigid, and the third most likely to St. Conran, also rendered as Cuman. He also noted that one of them carried the Irish name Tobur na b-fear, meaning the Men's Well, a designation that hints at some kind of gendered custom or separation in how the wells were used, though the precise nature of that arrangement has not survived. The three wells did not exist in isolation. Within roughly ninety metres to the northwest lie the remains of St. Brigid's Church, a separate holy well dedicated to that saint, and a building that may have been known in the same century as the Court of St. Brigid, suggesting a small but coherent sacred landscape rather than a solitary spring. A further possible well has been identified in the field about seventy-eight metres to the north-northeast. The spring now enclosed within the pump house is considered a candidate for one of Colgan's three fountains, though which of the three it represents remains uncertain. Holy wells in Ireland were typically natural springs invested with spiritual significance and associated with particular saints, often serving as sites of pilgrimage and ritual long before and after the formal adoption of Christianity. At Killarecastle, the combination of a named church, a named court, and three named wells suggests a place of some local importance, even if its fame never spread far beyond the townland.