Barnham Water Hardness & Quality Report (2026)

Southern Water supplies Barnham, a rural West Sussex village near Bognor Regis in the Arun Valley — a community of thatched flint cottages and 1930s development in the coastal plain below the South Downs, adjacent to Barnham Station on the London–Brighton coast line and close to the Fontwell racecourse — from South Downs Chalk aquifer boreholes in the west Sussex coastal supply zone, treated at Hardham Water Treatment Works near Pulborough on the River Arun. At 285 mg/L (20.0°Clark) and a TDS of 784.4 mg/L, Barnham's water is very hard — consistent with the productive Cretaceous Upper Chalk of the South Downs that delivers persistently very hard groundwater to the West Sussex coastal plain communities.

Barnham lies in the West Sussex coastal plain south of the South Downs where the Upper Chalk aquifer freely discharges into the coastal spring and borehole system. Southern Water draws on South Downs chalk boreholes throughout the Arun Valley supply zone to produce 285 mg/L with TDS 784.4 mg/L — very hard chalk water consistent with the wider west Sussex and coastal plain supply from Chichester (280 mg/L) and Arundel through Barnham to Bognor Regis in the same South Downs chalk distribution tier.

At 285 mg/L, limescale is a severe and persistent household problem in Barnham. 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. A whole-house water softener is strongly recommended for Barnham households seeking to protect appliances and fittings from the very hard South Downs chalk supply.