Grantham Water Hardness & Quality Report (2026)

Grantham, the south Lincolnshire market town on the River Witham at the foot of the Lincoln Edge, is supplied by Anglian Water from the Lincolnshire Limestone (also called the Lincolnshire Oolite) aquifer and the River Witham catchment. The Lincolnshire Oolite is a productive Jurassic oolitic limestone aquifer forming the Lincoln Edge escarpment immediately west of Grantham — a pale, permeable limestone of considerable depth and productivity. Anglian Water draws from licensed boreholes in the Lincolnshire Oolite directly at Grantham, where the limestone is at shallow depth on the edge of the escarpment, and from the Witham valley. The oolitic limestone dissolves very high calcium in the short percolation path, delivering hard groundwater with high dissolved calcium and bicarbonate typical of Jurassic oolitic limestone supply zones.

Grantham's hard water — 209.5 mg/L (14.7°Clark) — reflects the Lincolnshire Oolite aquifer at the Lincoln Edge, where the Jurassic oolitic limestone produces some of the hardest water in Lincolnshire. The Drinking Water Inspectorate (DWI) classifies this supply as hard.

Limescale is a persistent household challenge in Grantham. At 209.5 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 Grantham households on the Lincolnshire Limestone supply.