Andover Water Hardness & Quality Report (2026)

Andover, the north Hampshire market town on the River Anton in the upper Test valley, is supplied by Southern Water from the River Test catchment and the Hampshire Chalk Aquifer. The River Anton rises from chalk springs in the chalk of the Hampshire Downs north of Andover — a true chalk stream fed entirely from the Cretaceous Upper Chalk of the north Hampshire plateau. Southern Water draws from chalk boreholes in the north Hampshire chalk (the chalk of the Test and Anton valley headwaters) and from the chalk spring-fed Test and Anton. The north Hampshire chalk here is the chalk of the Hampshire Downs — the same chalk formation as the Test valley below Andover — but at higher elevation with somewhat less recharge and slightly lower hardness than the main Test valley spring zones.

Andover's moderately hard water — 167 mg/L (11.7°Clark) — reflects the Hampshire Chalk Aquifer in the upper Test/Anton headwater zone, where the chalk produces moderately high dissolved calcium. The Drinking Water Inspectorate (DWI) classifies this supply as moderately hard.

Limescale is a regular household concern in Andover. At 167 mg/L, limescale forms in kettles within three to four weeks and monthly descaling is sensible. Combi-boiler heat exchangers accumulate deposits at a moderate rate; annual servicing is recommended. Showerheads and taps develop regular deposits. Washing-up liquid lathers moderately. Using Calgon monthly in the washing machine and a regular descaling routine is appropriate limescale management for Andover households on the Hampshire chalk supply.