Stourbridge Water Hardness & Quality Report (2026)

Stourbridge, in the Metropolitan Borough of Dudley in the south-west Black Country, is supplied by Severn Trent Water from the Elan Valley Reservoir system in mid-Wales delivered via the West Midlands Aqueduct to Frankley Water Treatment Works south of Birmingham. The Elan Valley supply — drawing from the soft upland Welsh reservoirs of the Elan and Claerwen catchments draining ancient Ordovician and Silurian rocks — provides the dominant, very soft supply baseline for the West Midlands network. Stourbridge's south Dudley position, closer to the Elan Valley supply origin than more easterly Midlands towns, receives a blend with a higher proportion of soft Elan Valley water and a more modest increment from local Triassic sandstone and Black Country coal measures groundwater contributions.

Stourbridge's hardness of 114.5 mg/L (8.0°Clark) reflects the strong Elan Valley soft-water supply dominance in the south Dudley distribution zone, with only a modest local groundwater increment. This is softer than Kidderminster (180 mg/L) and Halesowen (148 mg/L), suggesting a higher Elan Valley proportion in the Stourbridge supply blend. The Drinking Water Inspectorate (DWI) classifies this supply as moderately soft.

Limescale is a moderate concern in Stourbridge. At 114.5 mg/L, limescale forms gradually and kettles need descaling every one to two months. Combi-boiler heat exchangers accumulate modest deposits; annual servicing is sensible. Showerheads and taps develop light deposits. Washing-up liquid lathers reasonably well. A monthly Calgon tablet in the washing machine and a regular kettle descale is adequate limescale management for most Stourbridge households on the Elan Valley supply.