Wath upon Dearne Water Hardness & Quality Report (2026)

Yorkshire Water supplies Wath upon Dearne, a former mining and glassmaking town in the Dearne Valley of Rotherham, from a blend of Pennine upland reservoir supply and Magnesian Limestone (Permian Zechstein) groundwater in Yorkshire Water's South Yorkshire distribution network, treated at regional South Yorkshire works. At 135 mg/L (9.5°Clark), Wath upon Dearne's water is moderately soft — a balance between the very soft Pennine reservoir sources and the harder limestone groundwater from the eastern South Yorkshire belt that characterises this part of the Dearne valley supply zone.

The soft Pennine reservoir water from the Millstone Grit Series moorland catchments of West Yorkshire dilutes the harder Magnesian Limestone groundwater in the Yorkshire Water distribution network. The Dearne Valley sits in the transition zone between the soft-water coalfield and the harder limestone belt east of Rotherham. Wath's position in the western Dearne valley places it closer to the soft-water Pennine blend than the harder eastern limestone communities like Maltby (182.5 mg/L), producing the moderately soft 135 mg/L supply recorded here.

At 135 mg/L, Wath upon Dearne's water is moderately soft with comfortable domestic properties. Descaling the kettle every six to eight weeks is typically adequate. The combi-boiler benefits from a fitted scale inhibitor as a standard precaution. Washing-up liquid lathers satisfactorily at everyday quantities. Taps and shower heads develop light limescale deposits over a few weeks; a monthly wipe with white vinegar or a mild descaler keeps fixtures in good condition. The moderately soft water is characteristic of the Dearne Valley's mixed supply geography, where Pennine and Magnesian Limestone sources combine.