Esher Water Hardness & Quality Report (2026)

Esher, in the Borough of Elmbridge in Surrey on the north slope of the North Downs at the Thames–Mole confluence, is supplied by Thames Water from the Thames storage reservoir system at Walton-on-Thames — immediately adjacent to Esher — and from the Mole Valley Chalk Aquifer contributions. Thames Water's Walton Water Treatment Works is at Walton-on-Thames adjacent to Esher, abstracting from the Thames and treating for distribution to the Elmbridge and Esher area. The River Mole — a chalk-fed stream draining the North Downs chalk from Dorking northward through Leatherhead to the Thames at East Molesey near Esher — is a significant chalk-stream tributary, contributing dissolved calcium from the Surrey chalk. The Thames at Walton carries accumulated chalk-stream chemistry from the Mole, Wey, and other chalk tributaries.

Esher's hardness of 215.5 mg/L (15.1°Clark) reflects the Thames supply from Walton, enriched by the River Mole and North Downs Chalk tributary chemistry. Esher's proximity to the Walton Thames intake means it receives fresh treated Thames supply with relatively high chalk-stream calcium from the Mole Valley drainage of the Surrey chalk. The Drinking Water Inspectorate (DWI) classifies this supply as hard.

Limescale is a persistent household challenge in Esher. At 215.5 mg/L, limescale forms in kettles within two to three weeks and monthly descaling is advisable. Combi-boiler heat exchangers accumulate deposits steadily — annual boiler servicing and an in-line scale inhibitor are recommended. Showerheads, taps, and shower screens develop regular deposits. Washing-up liquid lathers poorly. Using Calgon monthly in the washing machine and maintaining a regular descaling routine is important limescale management for Esher and Elmbridge households on the Thames Valley chalk supply.