Threipmuir Reservoir

Threipmuir Reservoir lies two miles south of Balerno, at the foot of the Pentland Hills, south of Edinburgh. It is an earth-dammed body of water built between 1843 and 1848 by the Edinburgh Water Company under engineer James Jardine to hold back the Water of Leith. The spillway at the eastern end sends surplus water on to Harlaw Reservoir. On the southern shore stands Bavelaw Castle, a 16th-century ruin. The reservoir gained national notice in 2025 when conservationists moved rare Round-leaved bryum moss here from its single remaining British site. The moss had vanished from Threipmuir decades earlier and now thrives again in the loch. Edinburgh’s Water of Leith Flood Prevention Scheme keeps the valley safe downstream. Visitors walk the flat shoreline path that circles the water, watching for herons and waterfowl. The Pentland Hills rise steeply behind, offering short climbs to viewpoints over the reservoir. On calm days the reflections of the hills and castle ruins double the scene. Anglers fish from the western bank where the Water of Leith enters. The air carries the scent of heather and damp grass, typical of the upland edge of the city.