Neath Water Hardness & Quality Report (2026)

Neath, the south Wales town in Neath Port Talbot on the River Neath, is supplied by Dŵr Cymru Welsh Water from Llyn Brianne reservoir in the upper Tywi valley in Carmarthenshire and the upper River Neath upland catchments. Llyn Brianne is the principal water supply reservoir for south-west and west Wales, impounding the upper Tywi on Devonian Old Red Sandstone and Silurian moorland in the Cambrian Mountains. The upper Neath catchment above Glynneath drains the Carboniferous Millstone Grit and sandstone moorland of the Brecon Beacons fringe. Both the Llyn Brianne and upper Neath catchments drain insoluble ancient rock formations, producing very soft water. Welsh Water treats and distributes to Neath and the Neath valley.

Neath's soft water — 61.5 mg/L (4.3°Clark) — reflects the Devonian Old Red Sandstone and Carboniferous Millstone Grit moorland catchment chemistry of the Welsh Water south Wales upland supply. The ancient sedimentary moorlands of the Brecon Beacons fringe are essentially calcium-free, and the TDS of 102.8 mg/L confirms very low mineral content. The Drinking Water Inspectorate Wales classifies this supply as soft.

Limescale is very minor in Neath. At 61.5 mg/L, limescale builds slowly and kettles need descaling every two to three months. Combi-boiler heat exchangers accumulate minimal deposits; annual servicing is routine good practice. Showerheads and taps remain largely clear. Washing-up liquid lathers very well. Limescale is not a significant domestic concern for Neath households on the Welsh Water upland reservoir supply.