Dudley Water Hardness & Quality Report (2026)

Dudley's water supply is managed by South Staffordshire Water, a water-only company serving the Black Country and parts of Staffordshire. Supply is drawn from a blend of surface water abstracted from the River Severn at Trimpley Water Treatment Works near Bewdley in Worcestershire, supplemented by licensed boreholes into the Triassic Sherwood Sandstone and Mercia Mudstone aquifer systems beneath the West Midlands. Unlike neighbouring Birmingham, which is predominantly supplied by the very soft Elan Valley Welsh reservoirs via Severn Trent Water's aqueduct, Dudley's supply from South Staffordshire Water draws a significantly higher proportion from local West Midlands groundwater, which naturally carries greater dissolved mineral content. Water is treated and distributed across the Metropolitan Borough of Dudley and the surrounding Black Country.

Dudley's hardness of 179.5 mg/L (12.6°Clark) reflects the groundwater contribution from the West Midlands basin geology. The Sherwood Sandstone and Mercia Mudstone of the Triassic period underlie much of the Black Country plateau. These sedimentary formations, deposited in warm, arid continental environments over 230–250 million years ago, have accumulated dissolved calcium and magnesium from overlying Carboniferous limestone and dolomitic beds. River Severn abstractions also carry modest calcium content from upstream limestone outcrops in Shropshire and the Welsh Marches. The blended result is classified as moderately hard by the Drinking Water Inspectorate (DWI).

Limescale is a regular household concern in Dudley. At 179.5 mg/L, limescale forms in kettles within three to four weeks of daily use and monthly descaling with a commercial descaler or diluted citric acid is advisable. Combi-boiler efficiency is affected over time — limescale accumulates in the heat exchanger steadily at this hardness, and annual boiler servicing with a limescale inspection is important. Showerheads and taps develop deposits at a steady rate. Washing-up liquid lathers moderately but noticeably less than in soft-water areas. Fitting a scale inhibitor to the boiler cold feed and using Calgon monthly in the washing machine is sensible protection for Dudley households.