Salisbury Water Hardness & Quality Report (2026)

Salisbury, the Wiltshire cathedral city at the confluence of the Avon, Bourne, Nadder, Wylye, and Ebble — all chalk streams draining the Wiltshire chalk downs — is supplied by Wessex Water from the Hampshire Avon catchment and the Wiltshire Chalk Aquifer. All five rivers meeting at Salisbury are true chalk streams: fed entirely or predominantly by chalk springs rising from the Cretaceous Chalk of the Marlborough Downs, Cranborne Chase, and the Wiltshire chalklands. Wessex Water draws from chalk boreholes and chalk spring abstraction points in the Avon and Wylye valleys, treating at Codford and Wilton Water Treatment Works and distributing to Salisbury. The chalk here is the same continuous Cretaceous Chalk formation of Wiltshire and Hampshire producing very hard water across the region.

Salisbury's very hard water — 271 mg/L (19.0°Clark) — reflects the Wiltshire Chalk Aquifer and chalk-stream supply characteristic of the Wiltshire downland Avon catchment. The TDS of 782.3 mg/L confirms very high mineral content typical of pure chalk spring water. The Drinking Water Inspectorate (DWI) classifies this supply as very hard.

Limescale is a very serious daily challenge in Salisbury. At 271 mg/L, thick limescale forms in kettles within one to two weeks requiring fortnightly descaling. Combi-boiler heat exchangers face serious limescale risk — annual boiler servicing and a polyphosphate scale inhibitor are essential. Showerheads, taps, and shower screens develop very heavy deposits. Washing-up liquid lathers very poorly. Salisbury homeowners should strongly consider a whole-house water softener for comprehensive protection against the very hard Wiltshire chalk supply.