Portslade Water Hardness & Quality Report (2026)

South East Water supplies Portslade, a western suburb of Brighton and Hove, drawing from a combination of deep chalk boreholes in the South Downs and surface water from the River Adur catchment, treated at Falmer Water Treatment Works and other Sussex facilities before distribution across Brighton and Hove. At 253.5 mg/L (17.8°Clark), Portslade's water is very hard, driven by the dominant chalk geology of the South Downs that sits immediately to the north and extends as a thick, productive aquifer beneath the coastal strip.

The South Downs between Brighton and Chichester are underlain by some of the thickest sections of Upper Cretaceous Chalk in England — steeply dipping beds of Turonian and Senonian chalk that form the smooth downland escarpment familiar to walkers. Groundwater infiltrating this chalk percolates through hundreds of metres of porous rock, dissolving calcium carbonate at every stage. Boreholes into the chalk at Falmer and across the eastern South Downs yield highly mineralised water with very high bicarbonate hardness that defines the water quality of Brighton and its surroundings.

Limescale is a significant daily challenge in Portslade. Kettles should be descaled fortnightly to prevent element degradation and calcium particles in drinks. The combi-boiler requires a fitted scale inhibitor — essential at this hardness level — and annual servicing to check for heat exchanger deposits. Washing-up liquid produces noticeably less lather in this very hard water; more product is needed per wash than the bottle suggests. Taps, shower screens, and basin mixers develop heavy limescale deposits within a week or two; a fortnightly descaling wipe with white vinegar or a proprietary product is recommended, and a whole-house water softener is strongly recommended for comprehensive long-term protection.