Hitchin Water Hardness & Quality Report (2026)

Hitchin, the north Hertfordshire market town on the River Hiz — a chalk stream that rises directly from chalk springs at Hitchin itself — is supplied by Affinity Water from the Hertfordshire Chalk Aquifer and chalk boreholes in the north Hertfordshire chalk plateau. Affinity Water draws from the Cretaceous Chalk of north Hertfordshire, where the Hiz valley chalk springs and local chalk boreholes yield moderately hard groundwater typical of the north Hertfordshire chalk. The north Hertfordshire chalk is the Chiltern and East Anglian chalk belt at its more northerly range, and the hardness at Hitchin (173 mg/L) is somewhat softer than the deeper, more concentrated chalk supply zones of south Hertfordshire such as Borehamwood (216 mg/L) and Cheshunt, reflecting the thinner chalk and shallower borehole depths here.

Hitchin's hardness of 173 mg/L (12.1°Clark) reflects the Cretaceous Chalk of north Hertfordshire in Affinity Water's Hitchin supply zone. The Drinking Water Inspectorate (DWI) classifies this supply as moderately hard.

Limescale is a regular household concern in Hitchin. At 173 mg/L, limescale forms in kettles within three to four weeks and monthly descaling is sensible. Combi-boiler heat exchangers accumulate deposits at a moderate rate; annual servicing is recommended. Showerheads and taps develop consistent deposits. Washing-up liquid lathers moderately. Using Calgon monthly in the washing machine and a regular descaling routine is appropriate limescale management for Hitchin households on the Affinity Water chalk supply.