Glencorse Reservoir

Glencorse Reservoir lies two miles west of Glencorse in Midlothian, set within the Pentland Hills. An earth dam holds back the water, built between 1820 and 1824 by James Jardine. It was designed to feed mills at Auchendinny, Milton Bridge and Glencorse, and to carry drinking water to Edinburgh. The dam stands 23.5 metres high, one of the tallest in Britain when completed. Construction proved difficult because a spur of rock narrowed the Glencorse Burn’s channel. Excavating a deep gravel bed caused the hillside on the south to collapse. The reservoir covers 19.3 hectares and supplies water through a cast-iron pipe to smaller city reservoirs at Castlehill and near George Heriot’s School. A modern water treatment works opened in 2012 to replace older plants at Alnwickhill and Fairmilehead. By 2019 the Glencorse works could produce 175 million litres daily for up to 450,000 customers in Edinburgh and West Lothian. Beneath the surface lie the remains of St Catherine’s of the Hopes, a 13th-century chapel flooded when the reservoir was created. Visitors walk around the reservoir’s edge, where the Pentland Hills rise steeply. The dam’s broad crest offers views across the water to the surrounding hills. Paths lead through quiet woodland and open moorland, with glimpses of other reservoirs nearby. The water’s surface reflects the hills, and on calm days the scene is calm and remote. The remains of the old chapel lie hidden below the water, adding a sense of history to the landscape.