Bicester Water Hardness & Quality Report (2026)

Bicester, in Cherwell district in north Oxfordshire on the River Cherwell, is supplied by Thames Water from the River Cherwell catchment and the Jurassic Limestone and Oxfordshire Chalk aquifer of north Oxfordshire. The Cherwell rises in the Jurassic Great Oolite country of north Northamptonshire and flows south through Oxfordshire, draining the Jurassic Ironstone and oolitic limestone country of Banbury and the north Oxfordshire hills. Thames Water draws from the Cherwell and from the Cretaceous Chalk and Jurassic limestone aquifer of north Oxfordshire. Both the Jurassic limestone and the chalk contribute dissolved calcium — the Jurassic oolite of north Oxfordshire is highly permeable and dissolves moderate calcium. The result is a hard supply for the north Oxfordshire Thames Water zone.

Bicester's hard water — 211.5 mg/L (14.8°Clark) — reflects the Jurassic Limestone and Oxfordshire Chalk of Thames Water's north Oxfordshire Cherwell valley supply zone. The Drinking Water Inspectorate (DWI) classifies this supply as hard.

Limescale is a persistent household challenge in Bicester. At 211.5 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 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 Bicester households.