Prescot Water Hardness & Quality Report (2026)

Prescot, in the Metropolitan Borough of Knowsley in east Merseyside on the south Knowsley plain, is supplied by United Utilities from the Thirlmere Lake District aqueduct and the River Dee treated at Huntington Water Treatment Works near Chester. The Thirlmere aqueduct delivers very soft water from the Borrowdale Volcanic catchment of the central Lake District, and the Dee from its Snowdonian upland headwaters adds further soft water. Prescot's south Knowsley supply zone draws a relatively high proportion of the soft Thirlmere/Dee source supply with limited hard groundwater blending — somewhat softer than Kirkby (105.5 mg/L) in north Knowsley and considerably softer than Huyton (165 mg/L) in the east Knowsley zone. The south Prescot zone is fed more directly from the south Merseyside distribution network carrying predominantly soft supply.

Prescot's soft water — 97.5 mg/L (6.8°Clark) — reflects the soft Thirlmere and Dee supply dominant in the south Knowsley United Utilities distribution zone. The Drinking Water Inspectorate (DWI) classifies this supply as soft.

Limescale is minor in Prescot. At 97.5 mg/L, limescale builds slowly — kettles need descaling every two to three months. Combi-boiler heat exchangers accumulate minimal deposits; annual servicing is routine. Showerheads and taps remain largely clear. Washing-up liquid lathers well. Limescale is not a significant domestic concern for Prescot households on the United Utilities Thirlmere and Dee supply.