Greenock Water Hardness & Quality Report (2026)

Greenock, the Inverclyde Clyde estuary town on the south bank of the Clyde west of Glasgow, is supplied by Scottish Water from Loch Thom reservoir in the Renfrewshire Hills above the town. Loch Thom — historically fed via the famous Greenock Cut aqueduct, constructed in 1827 — collects water from the Renfrewshire Hills draining Devonian Old Red Sandstone and intrusive igneous rocks of the west Scotland uplands. The Renfrewshire Hills are composed of ancient volcanic and sedimentary rocks that contribute virtually no dissolved calcium, producing exceptionally soft, peat-stained moorland water. Scottish Water maintains and modernises the Loch Thom supply infrastructure and distributes to Greenock and Inverclyde. The low TDS of 89.4 mg/L confirms the very low mineral content of the Renfrewshire Hills supply.

Greenock's very soft water — 45.5 mg/L (3.2°Clark) — reflects the Old Red Sandstone and igneous Renfrewshire Hills catchment of Loch Thom. The Drinking Water Quality Regulator for Scotland classifies this supply as very soft.

Limescale is essentially absent in Greenock homes. At 45.5 mg/L, limescale will not form under normal domestic conditions — kettles need descaling only a couple of times a year and taps, showerheads, and shower screens remain completely clear. Washing-up liquid lathers exceptionally well with the very soft Loch Thom supply. The main consideration for Greenock households is the mildly corrosive nature of very soft water to older copper plumbing — Scottish Water carefully manages pH but older properties with lead or copper pipes should be aware of the slightly elevated dissolution risk.