Roehampton Water Hardness & Quality Report (2026)

Thames Water supplies Roehampton in the London Borough of Wandsworth in south-west London, adjacent to Richmond Park and the Roehampton Estate. Supply is drawn from the River Thames treated at Hampton and Kempton Water Treatment Works and distributed via the Thames Water south-west London network. At 196.5 mg/L (13.8°Clark), Roehampton's water is moderately hard — somewhat softer than much of south London — reflecting the Thames Water distribution blend in the south-west London zone near the Hampton treatment works source.

The River Thames at Hampton arrives carrying chalk-derived calcium bicarbonate from the Chiltern Chalk and North Downs catchments. In the south-west London distribution zone close to the Hampton source works, the supply receives a smaller proportion of the most mineralised, longest-residence chalk aquifer fractions compared to zones further into the city that blend more groundwater or Lee Valley chalk supply. The result is a moderately hard supply at 196.5 mg/L — still definitively hard by national standards, but less extreme than the central and south London zones receiving more mineralised distribution fractions.

At 196.5 mg/L, limescale is a consistent daily concern in Roehampton. Kettles benefit from descaling monthly to maintain efficiency. The combi-boiler should be fitted with a scale inhibitor and serviced annually. Washing-up liquid requires more product than in softer areas to achieve satisfactory lather. Taps and shower heads develop visible white limescale within one to two weeks; a fortnightly wipe with white vinegar or a proprietary descaling solution keeps fittings clean and prevents hard-water staining from building up permanently on surfaces in this moderately hard Thames-river south-west London supply zone.