Abercarn Water Hardness & Quality Report (2026)

Welsh Water supplies Abercarn, the Caerphilly borough village at the Ebbw Valley where the Sirhowy and Ebbw rivers join — a former colliery and ironworks community at the heart of the south Wales coal country, with a long industrial heritage from Abercarn Colliery and the Cwmcarn Colliery, now a residential community in the lower Ebbw and Sirhowy valley — from Ynysyfro Reservoir in the Sirhowy Valley upland of the Gwent Valleys catchment, treated at Newport Water Treatment Works. At 79 mg/L (5.5°Clark), Abercarn's water is soft — consistent with the impermeable Carboniferous Coal Measures (Westphalian) and Millstone Grit upland of the south Wales valleys that contribute almost no calcium to the upland reservoir supply.

Abercarn lies at the confluence of the Ebbw and Sirhowy rivers in the south Wales valley corridor where Welsh Water delivers Ynysyfro Reservoir supply from the Sirhowy upland — a catchment of impermeable Carboniferous Coal Measures shale and sandstone with moorland peat. The result is 79 mg/L with TDS 144.8 mg/L — soft water with a low TDS/hardness ratio (1.83) characteristic of the Welsh Water Gwent Valleys and Newport distribution zone at Risca (78 mg/L) and Newbridge in the same upland reservoir supply corridor.

At 79 mg/L, limescale is a moderate and manageable domestic concern in Abercarn. Descaling the kettle every two to three months is typically adequate. The combi-boiler has low scaling risk. Washing-up liquid lathers readily with modest quantities. Taps and shower heads develop light deposits; a quarterly wipe with white vinegar keeps fixtures clean. Abercarn's soft supply reflects the south Wales valleys Coal Measures upland — the same impermeable shales that once yielded coal and iron from the valley floor providing clean, soft water from the upland reservoir to households throughout the Ebbw and Sirhowy valley corridor.