Stirling Water Hardness & Quality Report (2026)

Stirling, the historic Scottish city on the River Forth at the Gateway to the Highlands, is supplied by Scottish Water from Loch Katrine in the Trossachs and the west Scotland supply grid. Loch Katrine — made famous by Sir Walter Scott's poetry and the setting for the celebrated Victorian aqueduct system supplying Glasgow — is fed by the Dalradian schist and Grampian metamorphic catchments of the Trossachs. These ancient Caledonian metamorphic rocks of the southern Highlands are entirely calcium-free, producing exceptionally soft highland water of remarkable purity. Scottish Water distributes the Loch Katrine supply via the west Scotland grid, and Stirling's position at the Highland Boundary Fault places it within the catchment of this very soft Highland supply. The TDS of 39.2 mg/L confirms the extraordinary mineral purity of the Stirling supply.

Stirling's exceptionally soft water — 22.5 mg/L (1.6°Clark) — reflects the Dalradian schist and Trossachs metamorphic Highland catchment of Loch Katrine, producing water of very low mineral content. The Drinking Water Quality Regulator for Scotland classifies this supply as very soft.

Limescale is essentially absent in Stirling homes. At 22.5 mg/L, limescale will not form under any normal domestic circumstances — kettles need descaling very occasionally and taps, showerheads, and shower screens remain completely clear. Washing-up liquid lathers exceptionally well. The very soft Loch Katrine supply is slightly corrosive to older copper plumbing; Scottish Water carefully manages pH, and Stirling households in older properties should be aware of the mild dissolution risk and consider a calcite filter if concerned.