Shoreham-by-Sea Water Hardness & Quality Report (2026)

South East Water supplies Shoreham-by-Sea, a coastal town in West Sussex at the mouth of the River Adur. Supply is drawn from deep chalk boreholes in the South Downs and from surface water from the River Adur catchment, treated at Falmer Water Treatment Works and other Sussex facilities before distribution across the coastal strip west of Brighton. At 279 mg/L (19.6°Clark), Shoreham-by-Sea's water is very hard, driven by the dominant South Downs Chalk that rises immediately to the north and provides the primary groundwater source for the coastal communities of mid-Sussex.

The South Downs between Shoreham and Worthing are underlain by some of the thickest sections of Upper Cretaceous Chalk in south-east England. Groundwater infiltrating this chalk from the dip slope percolates through hundreds of metres of porous rock, dissolving calcium carbonate via the carbonic acid mechanism over long residence times. Boreholes on the South Downs above Shoreham yield highly mineralised water with very high bicarbonate hardness. The River Adur also drains the chalk downlands in its upper course and carries dissolved calcium that reinforces the hard character of the blended supply reaching the coast.

Limescale is a significant daily challenge in Shoreham-by-Sea. Kettles require descaling fortnightly to prevent element damage and calcium particles in drinks. The combi-boiler needs a properly fitted scale inhibitor to protect the heat exchanger from the sustained calcium load, and annual professional servicing is essential. Washing-up liquid produces noticeably less lather than in softer areas; considerably more product is needed per wash. Taps, shower screens, and basin mixers develop heavy limescale deposits within days to a week; a twice-weekly descaling wipe with white vinegar or a proprietary product is advisable, and a whole-house water softener is strongly recommended for long-term protection of appliances and plumbing.