Eastleigh Water Hardness & Quality Report (2026)

Eastleigh, the Hampshire town north of Southampton in the Itchen valley, is supplied by Southern Water from the Hampshire Chalk Aquifer and the River Itchen chalk-stream system. The River Itchen — one of England's finest chalk streams, rising from chalk springs in the Hampshire chalk country at Winchester — flows south through the Itchen valley past Eastleigh to Southampton. Southern Water draws on chalk springs and borehole abstractions in the Hampshire chalk — the Cretaceous Upper Chalk of the South Downs and Hampshire Downs that forms the downland north of Eastleigh and Winchester. The chalk spring water of the Itchen catchment carries very high dissolved calcium from prolonged chalk contact, producing the hard supply characteristic of the Hampshire chalk lowland.

Eastleigh's hard water — 222.5 mg/L (15.6°Clark) — reflects the Hampshire Chalk Aquifer and the Itchen chalk-stream chemistry. The Itchen is a classic chalk stream — a chalk-fed river of very high natural hardness — and Southern Water's supply for the Eastleigh and Southampton area draws heavily on this chalk system. The Drinking Water Inspectorate (DWI) classifies this supply as hard.

Limescale is a persistent household challenge in Eastleigh. At 222.5 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 fitting 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 Eastleigh households on the Hampshire chalk supply.