Cheam Water Hardness & Quality Report (2026)

Affinity Water supplies Cheam, the historic Surrey village in the London Borough of Sutton — a community with a medieval church, an ancient almshouse row, and a prosperous residential character straddling the old Surrey–Middlesex border, famous for its association with the Nonsuch Palace of Henry VIII whose deer park once stretched across the Cheam fields — from the North Downs Chalk (Cretaceous) aquifer boreholes in the Surrey–Sutton supply zone, treated at Bough Beech Water Treatment Works near Edenbridge. At 264 mg/L (18.5°Clark), Cheam's water is very hard — consistent with the deep productive Cretaceous Chalk aquifer of the North Downs that delivers persistently very hard, mineralised groundwater to the Affinity Water Surrey south London distribution zone.

Cheam lies at the foot of the North Downs chalk dip slope in the Sutton–Ewell corridor where Affinity Water draws from deep North Downs Chalk boreholes. The Upper Chalk aquifer delivers calcium carbonate-rich groundwater, while the Upper Greensand beneath the chalk contributes sulphate, producing 264 mg/L with TDS 691.9 mg/L — very hard water with an elevated TDS/hardness ratio (2.62) consistent with the North Downs chalk borehole supply characteristic of Affinity Water's Surrey south London distribution zone.

At 264 mg/L, limescale is a persistent and significant household problem in Cheam. Kettles should be descaled every two to three weeks. The combi-boiler needs a fitted scale inhibitor and annual professional servicing. Washing-up liquid requires generous quantities for adequate lather. Taps and shower heads develop substantial white chalk deposits within a week to ten days; a fortnightly descaling with white vinegar or a proprietary product keeps fittings in good condition. Cheam's very hard North Downs chalk supply is as reliably present in every household as the commuter trains on the nearby Sutton loop line — a permanent feature of domestic life in this south London chalk-belt suburb.