Stroud Water Hardness & Quality Report (2026)

Stroud, the west Gloucestershire town in the Stroud valleys at the foot of the Cotswold escarpment, is supplied by Severn Trent Water from the River Frome (Stroud Frome) and the broader Severn Valley water resources. The Frome catchment in the Stroud valleys drains the west-facing scarp of the Cotswold Jurassic Limestone — the Jurassic oolitic limestone plateau that forms the Cotswolds — and the Lower Lias clay vale below. The Stroud valleys cut deeply into the Cotswold limestone escarpment, and the Five Valleys and Frome catchment collect water with moderate limestone dissolution products from the Jurassic scarp limestone. Severn Trent Water treats Frome and Severn valley supply and distributes to Stroud and the surrounding district. The Cotswold limestone contribution is moderated by the softer Lias clay vale and Severn alluvial plain drainage.

Stroud's hardness of 125.5 mg/L (8.8°Clark) reflects the blend of Cotswold Jurassic Limestone scarp drainage and softer Lower Lias clay vale contributions in the Stroud valleys supply zone. The Jurassic oolitic limestone of the Cotswold scarp — Bathonian and Bajocian oolite — contributes moderate dissolved calcium to the valley rivers, but the dominant Severn Valley supply dilutes this. The Drinking Water Inspectorate (DWI) classifies this supply as moderately soft.

Limescale is a moderate concern in Stroud. At 125.5 mg/L, limescale forms gradually in kettles and descaling every one to two months is typically sufficient. Combi-boiler heat exchangers accumulate modest deposits; annual servicing is sensible. Showerheads and taps develop light to moderate deposits. Washing-up liquid lathers reasonably well. Adding Calgon monthly to the washing machine and a regular kettle descale provides adequate limescale management for most Stroud households on the Cotswold escarpment supply.