Washington Water Hardness & Quality Report (2026)

Washington, the new town in the City of Sunderland in the Tyne–Wear corridor, is supplied by Northumbrian Water from the River Wear catchment and the Kielder Transfer Scheme. The Wear catchment supply is drawn from Burnhope Reservoir and Waskerley Reservoir in the west Durham uplands, treated at Wearmouth Water Treatment Works, and distributed through the Wearside and Washington network. Washington New Town was designated in 1964 and built rapidly in the 1970s. The River Wear drains the North Pennines — crossing Carboniferous limestone country in upper Teesdale before passing through the County Durham coalfield basin — and contributes moderate dissolved calcium from limestone and Coal Measures strata in its catchment. Kielder-fed North Tyne transfer water adds a very soft component.

Washington's hardness of 117.5 mg/L (8.2°Clark) reflects the Wear catchment blend of soft North Pennine moorland and moderate Carboniferous limestone contributions. The upper Wear above Wearhead drains over Carboniferous Limestone country and the Great Limestone formation in west Durham, dissolving moderate calcium content. The Kielder transfer adds very soft Northumberland moorland water, diluting the Wear supply. The blend produces a moderately soft supply for Washington, comparable to other Northumbrian Water supply towns in the north-east corridor. The Drinking Water Inspectorate (DWI) classifies this supply as moderately soft.

Limescale is a moderate concern in Washington. At 117.5 mg/L, limescale forms gradually — kettles need descaling every one to two months and deposits on taps and showerheads accumulate slowly. Combi-boiler heat exchangers accumulate modest deposits; annual servicing is sensible. Washing-up liquid lathers reasonably well. The North East supply gives Washington easy limescale management — Calgon monthly in the washing machine and an occasional kettle descale is adequate maintenance for most households.