By the time the first Ordnance Survey six-inch map was produced in 1839, it was already marked as a ruin. What makes the structure quietly remarkable is its long reach back through documentary history, appearing not only on that nineteenth-century map but also on the Down Survey barony map of 1655 to 1656, suggesting continuous recognition of the site across centuries.

The mill's origins are rooted in the foundation of the Augustinian priory itself. A charter in the Ormond Deeds, dating to around 1204 to 1206, records a grant by Geoffrey FitzRobert permitting the priory to enclose fisheries and mill ponds, and to operate mills on land beneath the church of St Mary. The charter goes further, stating that FitzRobert's tenants were free to grind at the priory mills without fear of legal reprisal, a clause that hints at the economic and jurisdictional weight attached to milling rights in medieval Ireland. Scholarship suggests a watermill had stood at this location since the thirteenth century. By the fifteenth century, the building had been absorbed into the southern walled enclosure of the precinct, an area known as the prior's vill. When the monastery was dissolved in 1541, several water mills were listed among its former properties, with surviving records noting the tenants' obligation to provide labour for cleaning the mill when required.

What remains today is fragmentary but legible. The north end of the building is constructed in random coursing, using unhewn and roughly squared stones, with squared quoins at both corners. The east wall, preserved to a length of around 4.5 metres, is the best surviving section, and beneath it a segmental arch, formed from roughly squared voussoirs, still spans the millrace channel. The building straddles the stream entirely, a configuration that may indicate the use of a horizontal wheel, a type of simple mill common in Ireland and Scotland in which a wheel lying flat in the water drove the millstone directly above it without the need for complex gearing.