Ilkeston Water Hardness & Quality Report (2026)

Ilkeston, in east Derbyshire on the River Erewash near the Nottinghamshire border in the Erewash valley, is supplied by Severn Trent Water from the River Trent and the Permian Magnesian Limestone aquifer of the east Derbyshire/west Nottinghamshire border country. Severn Trent abstracts from the Trent valley at Sawley near Long Eaton and from licensed boreholes in the Magnesian Limestone east of Ilkeston. The Erewash valley occupies the junction between the Carboniferous Coal Measures (west) and the Permian Magnesian Limestone (east), and the Severn Trent supply for the Erewash valley zone blends Trent valley surface water with groundwater contributions from the Magnesian Limestone — a dolomitic limestone that contributes high calcium and magnesium to groundwater. Ilkeston's hardness is very similar to Long Eaton (226 mg/L) in the same east Derbyshire Erewash corridor.

Ilkeston's hard water — 222.5 mg/L (15.6°Clark) — reflects the blend of River Trent catchment supply and Permian Magnesian Limestone groundwater in the east Derbyshire Erewash valley Severn Trent supply zone. The Drinking Water Inspectorate (DWI) classifies this supply as hard.

Limescale is a persistent household challenge in Ilkeston. At 222.5 mg/L, limescale forms in kettles within two to three weeks and monthly descaling is advisable. Combi-boiler heat exchangers accumulate deposits steadily — annual boiler servicing and an in-line scale inhibitor are recommended. Showerheads, taps, and shower screens develop regular deposits. Washing-up liquid lathers poorly. Using Calgon monthly in the washing machine and maintaining a regular descaling routine is important limescale management for Ilkeston households.