Stranraer Water Hardness & Quality Report (2026)

Scottish Water supplies Stranraer, the south-west Galloway port town at the head of Loch Ryan — the principal ferry terminal for the Cairnryan Irish Sea crossings to Belfast and Larne, and a town that has served as the gateway between Scotland and Ireland for centuries, set in the fertile Rhinns of Galloway peninsula at the south-western tip of Scotland — from Black Loch reservoir on the Rhinns of Galloway plateau, treated at Stranraer Water Treatment Works. At 16.5 mg/L (1.2°Clark) and a TDS of just 27.8 mg/L, Stranraer's water is exceptionally soft — consistent with the impermeable Silurian and Ordovician greywacke, mudstone, and Granite (the Loch Ryan Granite) of the Rhinns of Galloway upland that yields almost no calcium to surface runoff.

Stranraer's supply comes from the Rhinns of Galloway upland — a landscape of ancient Silurian and Ordovician greywacke and mudstone intruded by Caledonian granites, with blanket peat moorland providing an impermeable catchment yielding virtually no calcium or dissolved solids. The result is 16.5 mg/L with TDS 27.8 mg/L — the same exceptionally soft values as Whitburn in West Lothian — characteristic of the south-west Scotland impermeable upland reservoir supply that spans the Galloway Uplands and the south-west coalfield.

At 16.5 mg/L, limescale is essentially not a domestic concern in Stranraer. Descaling the kettle a couple of times a year is all that is required. The combi-boiler has negligible calcium scaling risk. Washing-up liquid lathers very readily with minimal product. Taps and shower heads accumulate virtually no limescale. In older Stranraer properties with lead service pipes, residents should follow Scottish Water's precautionary guidance to run the cold tap briefly before drinking, as exceptionally soft, low-TDS water has elevated plumbo-solvent potential — a consistent precaution across the very soft south-west Scotland Galloway supply zone.