Cwm Mill is a single-storey weaving mill, standing on the west bank of the Afon Leri gorge. It has five bays, and is built of rubblestone with a pitched slate roof and wooden window frames with iron glazing bars. It was powered by a composite breatshot waterwheel at its east end, 13 feet (3.96 metres) in diameter and bearing the maker's name, 'Samuel Owens, Newtown Foundry, 1858'. The mill was operated as part of the Leri Mills (NPRN 40851) complex, and contained hand looms as well as powered looms. It was accessed by a wooden footbridge across the river which has been destroyed.
W J Crompton, RCAHMW, 21 October 2014.