Otley Water Hardness & Quality Report (2026)

Yorkshire Water supplies Otley, the market town on the River Wharfe in Wharfedale below the Chevin, in the City and Borough of Leeds, from Fewston Reservoir and Swinsty Reservoir in the Washburn Valley — a tributary of the Wharfe — together with the wider upper Wharfedale supply chain, treated at regional Wharfedale works. At 169 mg/L (11.8°Clark), Otley's water is moderately hard, reflecting the Washburn Valley and Wharfedale blend of Millstone Grit moorland reservoir water and Carboniferous Limestone spring contributions from the Yorkshire Dales.

Fewston and Swinsty reservoirs in the Washburn Valley — a wooded valley running south from the limestone dales above Pateley Bridge — drain the Millstone Grit and Lower Carboniferous sedimentary rocks of the Nidderdale/Washburn uplands. The upper Washburn and Nidd catchment includes the southern fringe of the Great Scar Limestone, contributing calcium spring water that blends with soft gritstone moorland runoff to produce a moderately hard supply. The resulting 169 mg/L with TDS 467.5 mg/L at Otley is consistent with the Wharfedale limestone-gritstone blend that characterises the lower Wharfe Valley towns.

At 169 mg/L, limescale is a noticeable household concern in Otley. Kettles benefit from descaling every four to six weeks to maintain element efficiency. The combi-boiler should be fitted with a scale inhibitor and serviced annually. Washing-up liquid requires slightly more product than in softer areas. Taps and shower heads develop moderate limescale deposits within two to three weeks; a monthly wipe with white vinegar keeps fixtures in good condition. The moderately hard Washburn Valley supply is characteristic of the lower Wharfedale towns including Otley, Burley-in-Wharfedale, and Menston.