Codicote Water Hardness & Quality Report (2026)

Affinity Water supplies Codicote, the Hertfordshire village in the Chiltern chalk upland between Welwyn and Hitchin — a pleasant rural community on the chalk ridge road, with a historic parish church, village green, and easy access to the chalk downland paths of the mid-Hertfordshire countryside, well positioned between the A1(M) and Welwyn Garden City for London commuters — from the Chiltern Chalk (Cretaceous) aquifer boreholes in the mid-Hertfordshire supply zone, treated at Oughtonhead Water Treatment Works near Hitchin. At 214 mg/L (15.0°Clark), Codicote's water is hard — consistent with the productive Cretaceous Chalk aquifer of the mid-Hertfordshire chalk ridge that delivers persistently hard, mineralised groundwater to the Affinity Water mid-Hertfordshire distribution zone.

Codicote lies on the mid-Hertfordshire Chiltern Chalk ridge in the Affinity Water supply zone. Affinity Water draws from deep chalk boreholes in the Welwyn–Codicote–Hitchin corridor, yielding 214 mg/L with TDS 518.9 mg/L — hard water with a moderate TDS/hardness ratio (2.42) consistent with predominantly chalk carbonate hardness from the mid-Hertfordshire chalk borehole supply, comparable to Welwyn Garden City and Knebworth in the same Affinity Water mid-Herts Chiltern chalk distribution zone.

At 214 mg/L, limescale is a persistent household challenge in Codicote. Kettles should be descaled monthly. The combi-boiler benefits from a fitted scale inhibitor and annual professional servicing. Washing-up liquid requires more product per wash. Taps and shower heads develop visible white limescale deposits within one to two weeks; a fortnightly wipe with white vinegar or a proprietary descaling product keeps fittings clean. Codicote's hard chalk supply is characteristic of the mid-Hertfordshire ridge — the great Chiltern Chalk formation visible on every flinty field and parish church flint wall also mineralising the water in every village cottage.