New Barnet Water Hardness & Quality Report (2026)

Affinity Water supplies New Barnet, a suburban residential area in the London Borough of Barnet at the Hertfordshire–London border near Hadley Wood and Cockfosters — the suburb that grew up around the Great Northern Railway station opened in 1850 — from London Basin Chalk boreholes and the Chiltern chalk aquifer fringe, treated at Cuffley Water Treatment Works in Hertfordshire. At 188.5 mg/L (13.2°Clark), New Barnet's water is hard, consistent with the chalk borehole groundwater supply that defines Affinity Water's quality across the north London–Hertfordshire chalk belt.

New Barnet sits at the northern edge of Greater London where the London Basin Chalk approaches the Chiltern escarpment fringe beneath the Hertfordshire plateau. Affinity Water supplies north Barnet, East Barnet, and the Hertfordshire margin communities from Upper Chalk boreholes in the Lee Valley and Colne Valley chalk belt, supplemented by the Chiltern chalk aquifer. The 188.5 mg/L with TDS 421.5 mg/L is characteristic of the Affinity Water north London–Hertfordshire chalk supply zone — moderately hard chalk borehole groundwater with a typical calcium bicarbonate character.

At 188.5 mg/L, limescale is a persistent household concern in New Barnet. Kettles benefit from descaling every three to four weeks. The combi-boiler should be fitted with a scale inhibitor and serviced annually. Washing-up liquid requires more product than in softer areas to achieve satisfactory lather. 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 and prevents chalk staining from accumulating on surfaces and around tap bases in this hard north London–Hertfordshire chalk belt supply zone.