Dunbar Water Hardness & Quality Report (2026)

Scottish Water supplies Dunbar, the east Lothian coastal town on the Firth of Forth — the birthplace of John Muir (1838–1914), the pioneering Scottish-American naturalist who founded the American national parks movement, with the John Muir Birthplace Museum in the town, a ruined castle on the harbour, and a setting on the dramatic East Lothian coast where the Lammermuir Hills meet the North Sea — from Hopes Reservoir in the Lammermuir Hills above Gifford, treated at Dunbar Water Treatment Works. At 53 mg/L (3.7°Clark), Dunbar's water is soft — consistent with the impermeable Silurian greywacke and Devonian Old Red Sandstone and the basalt and dolerite intrusions of the Lammermuir upland that contribute very little calcium to the reservoir catchment.

Dunbar draws supply from Hopes Reservoir in the Lammermuir Hills — a catchment of Silurian greywacke, mudstone, and Devonian Old Red Sandstone with blanket moorland and rough pasture yielding low-mineralisation water. The result is 53 mg/L with TDS 108.2 mg/L — soft water with a moderate TDS/hardness ratio (2.04) characteristic of the Scottish Water east Lothian Lammermuir reservoir supply zone at Haddington and North Berwick in the same east Lothian supply distribution corridor.

At 53 mg/L, limescale is a minimal household concern in Dunbar. Kettle descaling every two to three months is all that is typically required. The combi-boiler has very low scaling risk. Washing-up liquid lathers readily with small quantities. Taps and shower heads accumulate very little limescale; a quarterly wipe keeps fixtures clean. Dunbar's soft Lammermuir supply is as clean as the coastal air on the East Lothian shore that John Muir knew as a boy — the impermeable upland that inspired America's greatest conservationist also providing some of Scotland's softest and least mineralised tap water.