Wallington Water Hardness & Quality Report (2026)

Thames Water serves Wallington in the London Borough of Sutton, supplying blended water drawn from the River Thames abstracted at Hampton and the River Lee at Coppermills Water Treatment Works, delivered via the Thames Water ring main across south London. At 246 mg/L (17.3°Clark), Wallington sits at the upper end of the hard category, driven by the chalk-dominated geology of the Thames catchment and the sustained contribution of groundwater from the North Downs Chalk aquifer underlying this part of south London.

The Thames Basin Chalk and overlying Tertiary sands and gravels form the geological context for Wallington's supply. The River Thames drains the Chiltern Chalk and North Downs Chalk extensively in its upper reaches, accumulating high dissolved calcium concentrations that survive into the treated distribution network. The North Downs themselves underlie much of Surrey and the London Borough of Sutton, contributing groundwater with very high calcium hardness to the blended municipal supply. This dual chalk input — from river abstraction and local aquifer contributions — sustains Wallington's elevated hardness throughout the year.

Limescale is a persistent household issue in Wallington. Kettles should be descaled monthly, with fortnightly descaling preferable for households that use the kettle frequently. The combi-boiler benefits from a fitted scale inhibitor and annual servicing to check for calcium deposits in the heat exchanger. Washing-up liquid requires more product than in softer-water areas to achieve a good lather, and rinse residues may leave a film on glassware if not thoroughly rinsed. Taps and shower heads develop visible white limescale deposits within a week or two and benefit from fortnightly treatment with white vinegar or a proprietary descaler. A scale inhibitor or water softener is recommended for long-term appliance protection.