Edgwarebury Water Hardness & Quality Report (2026)

Thames Water supplies Edgwarebury, a residential district at the northern fringe of Edgware in the London Borough of Barnet — a north London suburb at the Hertfordshire border, adjacent to the Edgwarebury Lane parkland corridor and the northern terminus of the former Edgware branch of the Northern line — from the River Lee chalk-tributary supply in the Thames Water north London distribution zone, treated at the Lee Valley Water Treatment Works complex. At 260.5 mg/L (18.3°Clark), Edgwarebury's water is very hard — consistent with the Thames Water north London Lee Valley chalk-dominant supply zone that produces persistently hard water throughout the north London Barnet/Hertfordshire fringe.

Edgwarebury sits at the north London fringe where Thames Water's Lee Valley chalk supply reaches the Barnet–Hertfordshire boundary. The Lee Valley chalk-tributary supply carries deeply mineralised chalk groundwater from Hertfordshire Chalk catchments through the Lee Valley reservoir chain to produce 260.5 mg/L with TDS 691.7 mg/L at Edgwarebury — very hard water consistent with the adjacent north London communities from Edgware (261 mg/L) and Stanmore (265 mg/L) in the same Thames Water north London Lee Valley distribution zone.

At 260.5 mg/L, limescale is a persistent and significant household problem in Edgwarebury. Kettles should be descaled every two to three weeks. The combi-boiler needs a fitted scale inhibitor and annual professional servicing. Washing-up liquid requires generous quantities for adequate lather. Taps and shower heads develop substantial white chalk deposits within a week to ten days; a fortnightly descaling with white vinegar or a proprietary product keeps fittings in good condition. A whole-house water softener is worth serious consideration for Edgwarebury households to protect appliances from the very hard north London Lee Valley chalk supply.