Greenford Water Hardness & Quality Report (2026)

Greenford, in the London Borough of Ealing in outer west London on the northern Brent valley plain, is supplied by Thames Water from the Chiltern Chalk Aquifer and River Thames storage reservoirs at the west London reservoir ring. Thames Water draws from chalk boreholes in the Cretaceous Chalk of the Chilterns extending south-east into the Thames valley — the chalk beneath the outer west London basin — and from the Thames reservoirs at Staines and the west London ring carrying chalk-stream calcium from the Thames tributaries. Greenford's outer west London position in the Ealing supply zone receives Thames Water's blend with a high chalk groundwater proportion, producing a very hard supply consistent with other outer west London zones. The TDS of 632.8 mg/L confirms high mineral content.

Greenford's very hard water — 246 mg/L (17.3°Clark) — reflects the Chiltern Chalk Aquifer influence on Thames Water's outer west London supply zone. The Drinking Water Inspectorate (DWI) classifies this supply as very hard.

Limescale is a very serious household challenge in Greenford. At 246 mg/L, limescale forms in kettles within one to two weeks requiring fortnightly descaling. Combi-boiler heat exchangers face serious limescale risk — annual boiler servicing and a polyphosphate scale inhibitor are essential. Showerheads, taps, and shower screens develop very heavy deposits. Washing-up liquid lathers very poorly. Greenford homeowners should strongly consider a whole-house water softener for effective protection against the very hard outer west London Thames supply.