Redhill Water Hardness & Quality Report (2026)

Redhill, in the Borough of Reigate and Banstead in Surrey at the Redhill Gap through the North Downs, is supplied by South East Water from the North Downs Chalk Aquifer in east Surrey. South East Water operates licensed chalk borehole abstractions in the Cretaceous Upper Chalk east and south of Redhill — the chalk of the North Downs plateau in the Reigate, Merstham, and Nutfield Marsh chalk country — as well as from the chalk accessible north and east of the Redhill/Reigate gap. The Redhill Gap is where the River Mole breaches the North Downs through a chalk water gap, and the chalk is particularly well developed and unconfined in this area, yielding productive hard groundwater. South East Water treats chalk supply at its Surrey facilities and distributes to Redhill and Reigate.

Redhill's hard water — 222.5 mg/L (15.6°Clark) — reflects the North Downs Chalk Aquifer in east Surrey at the chalk breach zone. The Cretaceous Upper Chalk of the Surrey North Downs is a productive, calcium-rich aquifer, and the Redhill/Reigate supply zone draws substantially from this chalk. The Drinking Water Inspectorate (DWI) classifies this supply as hard.

Limescale is a persistent household challenge in Redhill. 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 fitting 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 Redhill households on the east Surrey chalk supply.