Chesham Water Hardness & Quality Report (2026)

Affinity Water supplies Chesham, a market town in the Chiltern Hills of Buckinghamshire, via its Chiltern supply zone. Water reaching Chesham is drawn primarily from deep boreholes sunk into the Chiltern Chalk aquifer — one of the most productive in southern England — supplemented by surface water from the Chess Valley catchment. The River Chess rises as a spring directly from the chalk and has historically supplied the town, and this chalk-dominated hydrology gives Chesham's water its characteristic hardness, treated at Chesham and regional works before distribution at 239 mg/L (16.8°Clark).

The Upper Cretaceous Chalk of the Chilterns forms a broad escarpment and dip slope of highly porous, permeable rock extending through Buckinghamshire and into Hertfordshire. Groundwater percolates slowly through hundreds of metres of chalk matrix, dissolving calcium carbonate through the carbonic acid mechanism at every stage. The Chess Valley occupies a chalk dry valley where spring discharge from the chalk base has historically defined the local hydrology. Long groundwater residence times within the Chiltern chalk result in the high calcium bicarbonate concentrations observed in Chesham's supply.

Limescale is a consistent challenge in Chesham homes. Kettles should be descaled monthly, or fortnightly in households using the kettle heavily, to prevent element degradation and calcium flakes in drinks. The combi-boiler benefits from an in-line scale inhibitor and annual servicing to check for heat exchanger deposits. Washing-up liquid requires slightly more product than in softer-water areas to achieve a satisfactory lather. Taps and shower heads develop visible limescale deposits within one to two weeks; a fortnightly treatment with white vinegar or a proprietary descaler keeps fittings clean and prevents hard-water staining on surfaces.