Hailsham Water Hardness & Quality Report (2026)

Hailsham, the East Sussex market town in the Pevensey Levels between Eastbourne and the South Downs, is supplied by South East Water from the South Downs Chalk Aquifer. Hailsham itself sits on the Weald Clay and Pevensey Levels alluvium, but its domestic water supply is drawn from chalk boreholes in the adjacent South Downs — the chalk ridge rising from Eastbourne west through Lewes to the Hampshire border. South East Water abstracts from chalk boreholes in the Eastbourne and South Downs area, treating supply at Arlington and Eastbourne Water Treatment Works before distribution north-west to Hailsham. The high TDS of 651.9 mg/L at 263.5 mg/L hardness confirms deep chalk borehole water with extended mineral residence time, characteristic of the semi-confined chalk below the South Downs escarpment. At 263.5 mg/L Hailsham is very hard — among the hardest supplies in East Sussex, comparable to East Grinstead (262.5 mg/L) in West Sussex.

The Cretaceous Chalk of the South Downs at depth beneath the East Sussex coastal plain dips south, and where it is semi-confined below Gault Clay or alluvial drift, groundwater residence times increase and calcium bicarbonate accumulates to 250–270 mg/L. South East Water's Eastbourne zone draws on both the shallow unconfined chalk and the semi-confined chalk to the north — the blend producing a consistently hard supply at 260–265 mg/L in the Hailsham and Eastbourne hinterland area.

At 263.5 mg/L Hailsham's water is very hard and limescale is a serious domestic issue. Kettle elements require fortnightly descaling with concentrated citric acid. Shower screens develop a thick calcium crust without weekly chemical limescale treatment. Washing-up liquid must be used generously. Combi-boilers in Hailsham's mixed housing stock need inline scale inhibitors and regular servicing. Hailsham's pleasant East Sussex character — traditional market town, surrounding farmland and the dramatic South Downs backdrop — is contrasted by the very hard chalk water supply whose severity rivals any of the more famous hard-water zones of London's outer suburbs.