Hedge End Water Hardness & Quality Report (2026)

Southern Water supplies Hedge End, a large residential town in the Borough of Eastleigh east of Southampton in Hampshire. Supply is drawn from the Hampshire Chalk aquifer via major boreholes at Otterbourne in the Itchen Valley and from the Test Valley chalk sources, treated at Otterbourne Water Treatment Works before distribution across the Eastleigh, Hedge End, and Southampton eastern fringe supply zone. At 304.5 mg/L (21.4°Clark) and a TDS of 907.2 mg/L, Hedge End's water is very hard — among the hardest in Hampshire — reflecting the deep, confined chalk aquifer that underlies the Southampton basin.

The Hampshire Chalk forms a broad basin south of the North Downs and Salisbury Plain, recharged from the downs to the north and east. Groundwater percolating through the Upper Cretaceous Chalk of central Hampshire travels long distances underground before being abstracted at the Itchen Valley and Test Valley borehole fields, accumulating very high calcium bicarbonate concentrations over extended residence times in the confined aquifer. The resulting groundwater at nearly 1000 mg/L TDS and 304.5 mg/L hardness is among the most mineralised chalk groundwater in the region.

Limescale is an intense and constant challenge in Hedge End. Kettles must be descaled every one to two weeks to prevent rapid element failure and calcium particles in drinks. Combi-boilers face a very high risk of premature breakdown without a properly fitted, annually replaced scale inhibitor and regular professional servicing of the heat exchanger. Washing-up liquid requires substantially more product to produce any lather in this very hard water. Taps, shower screens, and basin mixers must be descaled weekly to prevent permanent hard-water staining, and a whole-house water softener is strongly recommended to protect all appliances, plumbing, and the boiler from severe limescale accumulation.