Cheltenham Water Hardness & Quality Report (2026)

Cheltenham, the elegant Regency spa town in Gloucestershire at the foot of the Cotswold escarpment, is supplied by Severn Trent Water from sources that include the River Severn and its Cotswold tributaries, including the River Chelt and the broader Cotswold spring network. Abstraction from the Severn upstream at Tewkesbury and the Cotswold spring feeder streams provides the primary raw water resource. The Cotswold Hills to the east of Cheltenham are underlain by Jurassic Oolitic Limestone — the same rock formations that produce the warm-toned building stone of the Cotswold towns — and springs draining through this limestone have elevated calcium content. Water is treated at Severn Trent's Gloucestershire facilities before distribution to Cheltenham and the surrounding vale.

Cheltenham's hardness of 188.5 mg/L (13.2°Clark) reflects the Cotswold Jurassic Limestone influence on its water supply. The Cotswold escarpment immediately east of Cheltenham — including the prominent plateau above Cleeve Hill — is formed from Inferior Oolite and Great Oolite Jurassic limestone, deposited in warm tropical seas approximately 165–170 million years ago. Rainfall percolating through this limestone and the spring-fed streams flowing off the dip slope carry dissolved calcium carbonate, contributing the characteristic hardness of Gloucestershire and Vale of Evesham water. Ironically, Cheltenham built its 18th-century spa fame on the natural mineral springs of the area — the same mineral-rich geology that underpins the town's drinking water hardness today. The supply is classified as moderately hard by the Drinking Water Inspectorate (DWI).

Limescale requires regular attention in Cheltenham homes. At 188.5 mg/L, limescale forms in kettles within three to four weeks and monthly descaling is advisable. Combi-boiler heat exchangers accumulate deposits steadily — annual servicing with a limescale check and an in-line scale inhibitor are recommended. Showerheads, taps, and bathroom surfaces develop regular limescale deposits. Washing-up liquid lathers moderately. Maintaining a monthly descaling routine and using Calgon in the washing machine are standard household practices for Cheltenham residents.