Royal Leamington Spa Water Hardness & Quality Report (2026)

Royal Leamington Spa, the Warwickshire spa town on the River Leam — a tributary of the Avon — is supplied by Severn Trent Water from the River Leam and Avon catchment supply and the Jurassic Limestone groundwater of the Warwickshire Feldon. Severn Trent draws on surface water abstractions from the Leam and Avon in the Warwickshire lowland, and from licensed boreholes in the Jurassic Lias and Inferior Oolite of the south Warwickshire plateau country. The Leam catchment drains the Jurassic limestone and clay country of the south Midlands — including the Blue Lias and Jurassic Lower Lias of the Feldon plateau south of Leamington — contributing moderate dissolved calcium from limestone dissolution. The town's celebrated spa waters historically drew on the natural saline and sulphurous groundwater of the Triassic and Liassic aquifer system.

Royal Leamington Spa's hardness of 151.5 mg/L (10.6°Clark) reflects the Jurassic Lias limestone and clay vale catchment chemistry of the Leam and Avon supply zone. The Jurassic Blue Lias and Lower Lias limestone interbedded with clays in the Warwickshire Feldon contribute moderate calcium to the Severn Trent supply blend. The Drinking Water Inspectorate (DWI) classifies this supply as moderately hard.

Limescale is a moderate household concern in Royal Leamington Spa. At 151.5 mg/L, limescale forms gradually in kettles and descaling every one to two months is typically sufficient. Combi-boiler heat exchangers accumulate deposits moderately; annual servicing with a limescale check is sensible. Showerheads and taps develop modest 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 Royal Leamington Spa households.