Northallerton Water Hardness & Quality Report (2026)

Yorkshire Water supplies Northallerton, the county town of North Yorkshire in the Vale of York. Supply is drawn from Cod Beck Reservoir in the Hambleton Hills and from Permian Magnesian Limestone groundwater beneath the Vale of York, treated at regional North Yorkshire works before distribution. At 206 mg/L (14.4°Clark), Northallerton's water is hard — harder than most North Yorkshire market towns — reflecting the significant contribution of Magnesian Limestone groundwater from the Permian Zechstein belt that runs northward through the eastern Vale of York and into County Durham.

The Magnesian Limestone (Permian Zechstein) forms an escarpment north and east of Northallerton, where the distinctive pale dolomitic limestone provides significant groundwater resources. This limestone yields water with elevated calcium and magnesium hardness through dissolution of both calcium carbonate and magnesium carbonate in the dolomite. The Cod Beck moorland reservoir provides softer surface water to the blend, but the proportion of Magnesian Limestone groundwater in the Northallerton distribution zone is sufficient to elevate hardness well above the Pennine reservoir baseline, producing the hard supply recorded here.

At 206 mg/L, limescale is a consistent domestic concern in Northallerton. Kettles benefit from descaling monthly to prevent element efficiency loss. 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 visible limescale within one to two weeks; a fortnightly wipe with white vinegar or a proprietary descaling solution keeps fittings clean. Northallerton's hard water, driven by the Magnesian Limestone of the Vale of York, is characteristic of many North Yorkshire towns east of the A1.