Houghton-Le-Spring Water Hardness & Quality Report (2026)

Houghton-le-Spring, in the City of Sunderland metropolitan borough in east County Durham, sits directly on the Permian Magnesian Limestone plateau that forms the coastal plateau of east County Durham. Northumbrian Water supplies the Sunderland area including Houghton-le-Spring from the Kielder Transfer Scheme blended with Permian Magnesian Limestone groundwater from coastal County Durham boreholes. The Magnesian Limestone — a pale dolomitic limestone of Permian age — forms the characteristic coastal plateau of County Durham from Hartlepool north to the Tyne, and at Houghton-le-Spring the limestone is directly at the surface. Northumbrian Water draws from Magnesian Limestone boreholes in this east Durham zone, producing water with elevated calcium and magnesium from dolomite dissolution. The TDS of 587.7 mg/L — high relative to hardness — reflects elevated magnesium from the dolomitic limestone.

Houghton-le-Spring's hard water — 201 mg/L (14.1°Clark) — reflects the Permian Magnesian Limestone plateau geology of east County Durham dominant in the Northumbrian Water Sunderland/east Durham supply zone, producing one of the hardest supply zones in north-east England. The Drinking Water Inspectorate (DWI) classifies this supply as hard.

Limescale is a persistent household challenge in Houghton-le-Spring. At 201 mg/L, limescale forms in kettles within two to three weeks and monthly descaling is advisable. Combi-boiler heat exchangers accumulate deposits steadily — annual boiler servicing and an in-line scale inhibitor are recommended. Showerheads, taps, and shower screens develop regular deposits. Washing-up liquid lathers poorly. Using Calgon monthly in the washing machine and maintaining a regular descaling routine is important limescale management for Houghton-le-Spring households.