Antrim Water Hardness & Quality Report (2026)

NI Water supplies Antrim town, situated on the north-eastern shore of Lough Neagh in Antrim and Newtownabbey, drawing water directly from Lough Neagh — the largest freshwater lake in the British Isles — treated at Dunore Point Water Treatment Works near Toomebridge before distribution across County Antrim. At 33.5 mg/L (2.4°Clark), Antrim's water is very soft, reflecting the predominantly basaltic and glacial catchments that drain into Lough Neagh from the surrounding Antrim Plateau and Ulster lowlands.

Lough Neagh is fed by several major rivers draining the Antrim Plateau — a broad upland of Palaeogene basalt (the same formation as the Giant's Causeway) — and by rivers from the drumlin-covered drumlinfields of mid-Ulster. The Antrim basalts are chemically resistant volcanic rocks with very low calcium carbonate content, producing naturally soft, slightly acidic runoff. Glacial till and lacustrine sediments in the lough catchment contain some calcium from eroded Carboniferous Limestone, contributing the trace hardness measured in the supply, along with treatment chemicals added to raise pH and stabilise the water for distribution.

At just 33.5 mg/L, Antrim's water is virtually limescale-free. Descaling the kettle a couple of times a year as a precaution is more than sufficient. The combi-boiler faces negligible limescale risk at this hardness level, though fitting a basic scale inhibitor remains sound practice. Washing-up liquid produces a generous lather with very small quantities in this very soft water. Taps and shower heads remain clean for months without dedicated descaling treatment. Residents with older lead or copper pipework should be aware that very soft water is more corrosive to metals; briefly flushing taps before drawing drinking water and considering a plumbosolvency reducer is advisable in older properties.