Oakham Water Hardness & Quality Report (2026)

Anglian Water supplies Oakham, the county town of Rutland — England's smallest historic county — a handsome market town with a Norman castle hall adorned with a remarkable collection of horseshoes (a tradition since the 14th century), and situated on the edge of Rutland Water, the largest man-made reservoir in England by surface area — from Rutland Water reservoir at Empingham and Jurassic Limestone (Great Oolite and Lincolnshire Limestone) aquifer boreholes in the Rutland–Leicestershire supply zone, treated at Empingham Water Treatment Works. At 250 mg/L (17.5°Clark) and a TDS of 712.6 mg/L, Oakham's water is hard with an elevated TDS/hardness ratio (2.85) — reflecting the Jurassic Oolitic Limestone (Great Oolite) and the overlying Oxford Clay that contribute calcium and sulphate to the Rutland Water catchment and the local groundwater supply blend.

Oakham sits in the Rutland–Leicestershire Jurassic limestone vale where Anglian Water supplies from Rutland Water (reservoir on the Jurassic clay and limestone strata) and Jurassic Oolitic Limestone boreholes. The Great Oolite and Lincolnshire Limestone aquifer contribute calcium carbonate, while the Oxford Clay and Jurassic evaporite beds contribute sulphate, producing 250 mg/L with TDS 712.6 mg/L — hard water characteristic of the Anglian Water east Midlands Jurassic limestone supply tier at Market Harborough (255 mg/L) and Melton Mowbray (245 mg/L) in the same supply zone.

At 250 mg/L, limescale is a persistent household challenge in Oakham. Kettles should be descaled monthly. The combi-boiler benefits from a fitted scale inhibitor and annual professional servicing. Washing-up liquid requires more product per wash. Taps and shower heads develop visible white limescale deposits within one to two weeks; a fortnightly wipe with white vinegar or a proprietary descaling product keeps fittings in good condition. Rutland's hard Jurassic limestone supply at Oakham is as characteristic of England's smallest county as the horseshoes on Oakham Castle's great hall walls — both are products of the ancient oolitic rock that shapes everything from the town's building stone to its tap water.