Frimley Water Hardness & Quality Report (2026)

Thames Water supplies Frimley, a Surrey town in the Borough of Surrey Heath near Camberley — home of the Frimley Park Hospital, the largest district general hospital in Surrey, and adjacent to Sandhurst Royal Military Academy and the Blackwater Valley — from North Downs Chalk boreholes in the north Surrey chalk belt, treated at Frimley Green Water Treatment Works in Surrey. At 300 mg/L (21.0°Clark) and a TDS of 872.2 mg/L, Frimley's water is extremely hard — among the hardest in Surrey — consistent with the productive, deeply saturated Upper Chalk aquifer of the north Surrey chalk zone that is recharged from the North Downs plateau above.

Frimley sits at the north Surrey fringe where the North Downs Upper Chalk (Cretaceous) dips northward beneath the Bagshot Sand heath country. Thames Water draws on chalk boreholes in the Frimley and north Surrey chalk zone, extracting highly mineralised calcium bicarbonate chalk groundwater with TDS 872.2 mg/L at 300 mg/L hardness — consistent with the extreme hardness pattern across the north Surrey chalk belt from Frimley through Guildford to Reigate, where the productive chalk aquifer delivers consistently hard water.

At 300 mg/L, limescale is an extreme and persistent household problem in Frimley. Kettles must be descaled weekly to prevent rapid element failure. The combi-boiler faces very high risk of premature breakdown without a properly fitted, annually replaced scale inhibitor and regular professional servicing. Washing-up liquid barely lathers without very generous quantities of product. Taps, shower heads, and basin fittings develop heavy chalk encrustation within days; a weekly descaling with white vinegar or a proprietary product is essential. A whole-house water softener is very strongly recommended for all Frimley households.