Cricklewood Water Hardness & Quality Report (2026)

Cricklewood, in the London Borough of Brent in north-west London, is supplied by Thames Water from the combined Thames reservoir and Lee Valley distribution network serving north-west London. Thames Water serves the Brent area from both the Thames storage reservoirs — treated at Walton and distributed through the west London network — and the Lee Valley chalk supply treated at Coppermills. The Cricklewood and Brent supply zone sits between the westward Thames reservoir supply corridor and the north-eastward Lee Valley supply corridor, receiving a blended supply that is somewhat softer than the more Lee Valley-concentrated inner north London zones (such as Stamford Hill). The proportional blend of the softer Thames reservoir supply and the harder Lee Valley chalk supply at this distribution node moderates the overall hardness.

Cricklewood's hardness of 186.5 mg/L (13.1°Clark) reflects the Thames–Lee Valley supply blend chemistry in the north-west London Brent distribution zone. This is notably softer than the 318 mg/L of Stamford Hill (more Lee Valley-dominant) or the 230–240 mg/L of west London Thames supply zones, suggesting a blend composition with significant Thames reservoir dilution of the Lee Valley chalk supply. The Drinking Water Inspectorate (DWI) classifies this supply as moderately hard.

Limescale is a regular household concern in Cricklewood. At 186.5 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 with a limescale check and an in-line scale inhibitor are 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 Cricklewood households.