Knaresborough Water Hardness & Quality Report (2026)

Yorkshire Water supplies Knaresborough, the historic market town above the River Nidd gorge in North Yorkshire near Harrogate, famous for its medieval castle and Mother Shipton's Cave, from Roundhill Reservoir and the Nidd Valley upland catchments in the Yorkshire Dales, treated at regional Harrogate area works. At 126 mg/L (8.8°Clark), Knaresborough's water is slightly hard, reflecting a modest blend of the soft Pennine Nidd Valley reservoir supply with contributions from the Great Scar Limestone and Millstone Grit geology of the upper Nidd catchment in the Nidderdale area of the Yorkshire Dales.

The River Nidd rises in the Yorkshire Dales above Lofthouse in Nidderdale — a dale flanked by Millstone Grit moorland and the northern edge of the Great Scar Limestone that creates the famous How Stean Gorge. Roundhill Reservoir and the Nidd Valley catchment drain this mixed geological terrain, incorporating modest limestone spring contributions alongside the softer gritstone moorland runoff. The resulting 126 mg/L supply with TDS 315.2 mg/L is the characteristic slightly hard water of the Harrogate and Knaresborough supply zone, reflecting the Nidderdale limestone and gritstone mix in the source catchment.

At 126 mg/L, limescale is a moderate and manageable domestic concern in Knaresborough. Descaling the kettle every six to eight weeks is typically adequate. The combi-boiler benefits from a standard scale inhibitor as a sensible precaution. Washing-up liquid lathers well at normal quantities. Taps and shower heads develop light deposits over several weeks; a monthly wipe with white vinegar keeps fixtures clean. The slightly hard Nidd Valley supply is characteristic of the beautiful North Yorkshire spa town zone, where the soft Pennine source is gently elevated by Yorkshire Dales limestone contributions.