Addlestone Water Hardness & Quality Report (2026)

Thames Water supplies Addlestone, a residential town in the Runnymede district of north-west Surrey between Chertsey and Weybridge on the River Wey at its Thames confluence, from the River Thames treated at Walton-on-Thames and Hampton works. At 212.5 mg/L (14.9°Clark), Addlestone's water is hard, consistent with the chalk-dominated Thames catchment supply that defines water quality across all Thames Water distribution zones throughout north-west Surrey and the Thames corridor.

Addlestone sits in the Thames flood plain between the River Wey and the River Thames, in an area historically served by Thames riverside waterworks since the nineteenth century. The River Thames at Walton carries chalk-derived calcium bicarbonate from the Chiltern Chalk and North Downs Chalk catchments far upstream. Thames Water's Walton treatment works processes this chalk-dominated supply and distributes it to Addlestone and the north Surrey Thames corridor via the regional distribution network. The 212.5 mg/L hardness with TDS 506 mg/L is characteristic of the moderately hard to hard chalk Thames supply across north Surrey.

At 212.5 mg/L, limescale is a consistent household challenge in Addlestone. Kettles should be descaled monthly to maintain element efficiency. The combi-boiler benefits from a fitted scale inhibitor and annual professional servicing. Washing-up liquid requires more product than in softer areas. 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 on surfaces in this hard chalk Thames-supplied north Surrey community.