Chichester Water Hardness & Quality Report (2026)

Chichester, the Roman cathedral city at the western foot of the South Downs in West Sussex, is served by Southern Water, which abstracts the majority of supply from deep boreholes sunk into the South Downs Chalk Aquifer. The South Downs rise directly to the north and north-east of the city, and their chalk dip slope allows large volumes of rainwater to percolate slowly into the confined chalk aquifer below. Water is treated at Hardham Water Treatment Works near Pulborough and at Eastergate Water Treatment Works in the Chichester coastal plain, then distributed throughout the Chichester coastal basin. Southern Water also uses a network of surface intakes from chalk-fed streams such as the River Lavant, which rises in the heart of the South Downs chalk.

The Upper Cretaceous White Chalk of the South Downs is an exceptionally pure bioclastic limestone with very high primary and secondary porosity. Rainwater percolating through this chalk becomes saturated in calcium bicarbonate relatively rapidly, reaching groundwater hardness values of 240–260 mg/L within the confined aquifer beneath the Chichester plain. The TDS of 652.9 mg/L reflects additional dissolved minerals including sulphate from the Lower Greensand and residual marine salts in the deeper coastal aquifer zones.

At 252 mg/L Chichester's tap water is very hard and limescale affects every aspect of household water use. Kettle elements fur up within a week or two of use and require fortnightly descaling with a citric acid or vinegar solution. Shower screens and glass surfaces develop persistent limescale films that require daily wiping or weekly chemical treatment. Washing-up liquid consumption is noticeably elevated. Combi-boilers and washing machines need inline scale inhibitors to prevent premature damage to heating elements and valves. A water softener provides the most effective long-term solution for Chichester homes, eliminating the daily limescale battle altogether.