Rossendale Water Hardness & Quality Report (2026)

Rossendale, the valley borough in east Lancashire in the former textile heartland of the Rossendale Fells, is supplied by United Utilities from upland moorland reservoirs in the Rossendale hills and the wider Lancashire Pennine network. United Utilities draws on the Irwell and Irwell tributary headwater reservoirs above the Rossendale valley — including Cowm Reservoir above Whitworth and the Greenbooth and Naden reservoirs above Rochdale — supplemented by the broader United Utilities Lancashire distribution grid. The Rossendale Fells catchments drain predominantly over Carboniferous Millstone Grit — the coarse Pennine sandstone that gives the Rossendale and east Lancashire moors their characteristic peatland character — producing soft water in the high-altitude reservoir systems.

Rossendale's hardness of 166.5 mg/L (11.7°Clark) is above the very soft Millstone Grit reservoir baseline, reflecting United Utilities' blended Lancashire network. The United Utilities distribution system integrates soft Pennine reservoir water with harder groundwater contributions from the Carboniferous Limestone of the Forest of Bowland fringe and the lower Ribble valley. This network blending raises the hardness from the very soft moorland reservoir value to the moderately hard range seen at Rossendale. The Drinking Water Inspectorate (DWI) classifies this supply as moderately hard.

Limescale is a regular household concern in Rossendale. At 166.5 mg/L, limescale forms in kettles within three to four weeks and monthly descaling is sensible. Combi-boiler heat exchangers accumulate deposits at a moderate rate; annual servicing with a limescale check and fitting a scale inhibitor are recommended. Showerheads and taps develop consistent deposits. Washing-up liquid lathers moderately. Using Calgon monthly in the washing machine and a regular descaling routine is appropriate limescale management for Rossendale households.