Rhosllannerchrugog Water Hardness & Quality Report (2026)

Rhosllannerchrugog — known locally as Rhos — the former north Wales coalfield town in Wrexham County Borough on the eastern edge of the Clwydian Hills, is supplied by Dŵr Cymru Welsh Water. Supply for the Wrexham area draws on the north Wales upland reservoir network, principally Llyn Alwen (Alwen Reservoir) in the Alwen valley on the Denbigh Moors and supplies from the River Dee catchment via the Dee abstraction at Huntington treated at Brenig and Bretton Water Treatment Works. The Alwen catchment drains the Silurian greywacke and Ordovician mudstone moorlands of the Hiraethog uplands — calcium-depleted ancient marine sediments yielding inherently very soft, low-mineral water. At 67.5 mg/L with TDS 116.5 mg/L, Rhosllannerchrugog's supply has a very low mineral content typical of the north Wales upland reservoir supply across Denbighshire and Wrexham, virtually identical to Rhyl (66.5 mg/L) on the coast further north.

The Silurian greywacke and mudstone of the Alwen and Hiraethog uplands are ancient deep-water marine turbidite sediments utterly lacking in calcium carbonate, generating very soft moorland runoff. The River Dee's mainstream at this latitude carries water primarily from soft Ordovician and Cambrian mountain catchments of Snowdonia, diluting any modest limestone influence from the lower Dee valley. The resulting 67.5 mg/L hardness in Rhosllannerchrugog reflects the strongly soft-water character of the north Welsh Water supply network across this region, where even an industrial town at the coalfield edge receives essentially mountain-quality reservoir water.

At 67.5 mg/L Rhos's water is soft and limescale is not a meaningful household concern. Kettles need descaling only every two to three months — a light citric acid rinse is all that is required. Shower screens remain clean for weeks without treatment. Washing-up liquid lathers freely. Combi-boilers and white goods have very low scaling risk. Rhosllannerchrugog's proud Welsh-speaking heritage as a mining community is matched by a water supply that comes directly from the upland moorlands that frame the town's western horizon.