Unlike the vertical waterwheel familiar from postcards and paintings, the horizontal mill, sometimes called a tide mill or more commonly a clack mill, placed its wheel flat beneath the millstone, driven directly by a jet of water channelled through a wooden or stone chute. This simpler, older design required no gearing and could be operated by a single person, making it well suited to the small agricultural communities of rural Connacht.

Horizontal-wheeled mills of this type were the dominant form of grain milling in early medieval Ireland, with hundreds recorded in the archaeological record from the sixth century onwards. They tended to be built on modest watercourses, streams and mill races rather than the substantial rivers needed to turn a large vertical wheel, and their remains are often subtle: a scatter of shaped stone, a slight depression where the millpond once sat, the faint line of a leat, the channel that carried water to the wheel. Killeenadeema, a parish in the barony of Loughrea, sits in an area of south Galway with a long agricultural history, and a mill here would have served the local farming community in grinding oats and other grain crops into meal.