Lewes Water Hardness & Quality Report (2026)

South East Water provides mains water to Lewes and surrounding areas in East Sussex, UK. The utility draws primarily from groundwater boreholes tapping the Chalk aquifer beneath the South Downs National Park. Key abstraction sites are located in the River Ouse valley near Lewes. Raw groundwater undergoes treatment at facilities like the Lewes Water Treatment Works, where it is filtered, disinfected with chlorine, and its pH adjusted before being sent to customers. The water supply network includes reservoirs and pumping stations, serving a broad region.

The water originates from the Upper Chalk Group, a permeable aquifer composed of Late Cretaceous white micritic limestone, often containing flint nodules. This calcareous bedrock, particularly in the karstic features and fractures of the South Downs geology, readily dissolves calcium. Such leaching from the soft, porous strata is typical for chalk-dominated aquifers in southeast England, resulting in a consistently hard water supply for residents.

This very hard water commonly causes significant limescale buildup, particularly in appliances like kettles, boilers, and showerheads. Such deposits can reduce appliance efficiency and shorten their lifespan by as much as 50%. Homeowners often notice scum on fixtures and may experience increased detergent usage and skin dryness. Regular descaling with household acids can help, and installing limescale filters is an option. For substantial mitigation, a water softener is strongly recommended to protect appliances, reduce staining, and potentially lower energy costs.