Reigate Water Hardness & Quality Report (2026)

Reigate, the Surrey market town at the foot of the North Downs escarpment between Redhill and Horley — famous for its sandstone tunnel under the high street and its proximity to the Surrey Hills AONB — is supplied by South East Water from the North Downs Chalk Aquifer and the Upper Greensand (Hythe and Folkestone Beds). South East Water operates chalk and greensand boreholes in the North Downs zone north of Reigate — the chalk forming the prominent scarp above the town and the Greensand forming the sandy shelf below the chalk escarpment. Supply is treated at Holmwood Water Treatment Works and adjacent borehole sources in the Mole valley before distribution south to Reigate. At 219.5 mg/L with TDS 515.3 mg/L (ratio 2.35), Reigate's supply is hard but less mineralised than Godalming (270.5 mg/L) further west in the Wey valley — reflecting the combination of chalk and greensand sources in the Mole valley supply zone. The Upper Greensand is a harder, calcareous sandstone that contributes calcium bicarbonate to the blend alongside the chalk borehole groundwater.

The Cretaceous Chalk of the North Downs above Reigate at 150–200 m OD is the Upper Chalk (Turonian–Campanian), dipping north-east beneath the Surrey lowland. Chalk groundwater at 20–50 m depth in the unconfined chalk above Reigate achieves calcium bicarbonate hardness of 220–230 mg/L — slightly softer than Godalming's more deeply confined zone. The Upper Greensand (Hythe Beds) at the chalk base contributes additional calcium from calcareous cement, supplementing the chalk supply. The blend produces a consistently hard 215–225 mg/L supply across the Reigate and Redhill zone.

At 219.5 mg/L Reigate's water is hard and limescale management is a regular domestic necessity. Kettles benefit from monthly descaling with a citric acid tablet. Shower screens develop a calcium film requiring regular white vinegar treatment. Washing-up liquid must be used generously. Combi-boilers benefit from inline scale inhibitor protection. Reigate's North Downs Surrey market-town character — the castle grounds, the medieval tunnel, the Surrey Hills backdrop — is defined by the same chalk and greensand landscape that determines the hardness of its domestic water supply.