Blyth Water Hardness & Quality Report (2026)

Blyth, the Northumberland port town on the North Sea coast south of Whitley Bay, is supplied by Northumbrian Water from the Kielder Transfer Scheme and the River Blyth catchment in south Northumberland. Kielder Reservoir delivers very soft upland water via the North Tyne aqueduct, and the River Blyth drains the Carboniferous coal measure country of south-east Northumberland and the Cramlington/Northumbrian coalfield — moderately insoluble rock formations that contribute a moderate calcium increment over the pure Kielder supply. Northumbrian Water treats and distributes through the south Northumberland supply network to Blyth and the Blyth valley coastal area. The blend of very soft Kielder supply with moderate south Northumberland catchment contribution produces the moderately soft hardness typical of coastal south Northumberland.

Blyth's hardness of 115.5 mg/L (8.1°Clark) reflects the blend of very soft Kielder supply and moderate south Northumberland Carboniferous coalfield catchment contribution in the Northumbrian Water south Northumberland coastal zone. The Drinking Water Inspectorate (DWI) classifies this supply as moderately soft.

Limescale is a moderate concern in Blyth. At 115.5 mg/L, limescale forms gradually — kettles need descaling every one to two months. Combi-boiler heat exchangers accumulate modest deposits; annual servicing is sensible. Showerheads and taps develop light deposits. Washing-up liquid lathers reasonably well. A monthly Calgon tablet in the washing machine and a regular kettle descale is adequate limescale management for most Blyth households.