Selsey Water Hardness & Quality Report (2026)

Southern Water supplies Selsey, the coastal community on the Selsey Peninsula in West Sussex — England's southernmost village (by population centre), a low-lying chalk and shingle peninsula between Pagham Harbour and Bracklesham Bay, known for its excellent RNLI lifeboat station, recreational diving on the many wrecks of Selsey Bill, and the great marine fossil beds of the Bracklesham Beds along the coast — from the South Downs Chalk (Cretaceous) aquifer boreholes beneath the Selsey coastal plain, treated at Hardham Water Treatment Works near Pulborough. At 279.5 mg/L (19.6°Clark) and a TDS of 768.2 mg/L, Selsey's water is very hard — consistent with the deep, productive Cretaceous Chalk aquifer of the South Downs that delivers persistently very hard, mineralised groundwater to the Southern Water Chichester and Selsey distribution zone.

Selsey lies on the Selsey Peninsula underlain by the Bracklesham Beds (Eocene marine sands) above the deep South Downs Chalk aquifer. Southern Water draws from deep chalk boreholes beneath the Selsey plain, with the chalk delivering calcium carbonate groundwater enriched by sulphate from the Upper Greensand sequence, producing 279.5 mg/L with TDS 768.2 mg/L — very hard water with an elevated TDS/hardness ratio (2.75) consistent with the Southern Water Chichester coastal chalk supply at Chichester (276 mg/L) and Bognor Regis in the same South Downs chalk distribution zone.

At 279.5 mg/L, limescale is a persistent and significant household problem in Selsey. 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. Selsey's very hard chalk supply matches the coastal geology — the South Downs chalk that creates the white cliffs of Beachy Head also mineralises the water of every bungalow on England's most southerly peninsula.