Wrexham Water Hardness & Quality Report (2026)

Wrexham, the largest town in north Wales in the Wrexham County Borough, is supplied by Dŵr Cymru Welsh Water from the River Dee catchment and Llyn Brenig reservoir in the Denbigh Moors. Welsh Water's primary north-east Wales supply draws from the River Dee — a large, productive river rising in the Cambrian Mountains near Bala Lake and flowing through the Vale of Llangollen — and from Llyn Brenig on the Mynydd Hiraethog (Denbigh Moors) plateau. The Dee catchment drains ancient Cambrian and Ordovician volcanic and sedimentary rocks in Snowdonia and the Bala area, producing soft water, supplemented by more mineralised Carboniferous Limestone drainage from the Clwydian Range to the east. Water is treated at Brenig Water Treatment Works before distribution to Wrexham and north-east Wales.

Wrexham's soft water — 95 mg/L (6.7°Clark) — reflects the predominantly soft Dee catchment and Denbigh Moors reservoir supply. Llyn Brenig drains the Silurian and Ordovician moorland of Mynydd Hiraethog, yielding very soft water. The River Dee's upper catchment drains ancient Cambrian and Precambrian rocks of the Berwyn Mountains, also yielding soft water. A modest calcium increment from Carboniferous Limestone drainage in the Clwydian Hills to the east raises the hardness slightly above the very soft Brenig baseline. The Drinking Water Inspectorate Wales classifies this supply as soft.

Limescale is minor in Wrexham. At 95 mg/L, limescale builds slowly and kettles need descaling every two to three months. Combi-boiler heat exchangers accumulate minimal deposits and annual servicing is sensible routine maintenance. Showerheads and taps develop only light deposits. Washing-up liquid lathers well with the soft north Wales supply. Limescale is not a significant concern for most Wrexham households — the Dee and Denbigh Moors supply makes it one of the softer large towns in north Wales.