Clevedon Water Hardness & Quality Report (2026)

Bristol Water supplies Clevedon, a coastal town in North Somerset on the Severn Estuary. The town's water comes primarily from Chew Valley Lake and Blagdon Lake, two large reservoirs in the Mendip Hills fed by surface runoff and groundwater from local catchments, treated at Chew Valley and Barrow water treatment works before distribution to the greater Bristol area and its surroundings. At 156 mg/L (10.9°Clark), Clevedon's supply reflects a moderately hard water typical of the Mendip catchment zone, where limestone geology adds meaningful hardness to the reservoir-sourced supply.

The Mendip Hills south of Clevedon are underlain by Carboniferous Limestone — a thick sequence of Visean reef and bedded limestones that form the core of the upland plateau. Groundwater moving through these formations dissolves calcium and magnesium carbonates readily, contributing a limestone-derived hardness component to the supply blend. Surface runoff from the carboniferous plateau also carries some dissolved calcium, so both direct and indirect inputs from Mendip limestone elevate the hardness of Chew Valley and Blagdon reservoir water above what purely soft-rock catchments would produce.

At 156 mg/L, limescale accumulates at a moderate rate in Clevedon homes. The kettle benefits from descaling every four to six weeks to maintain heating efficiency and prevent calcium flakes in hot drinks. The combi-boiler should be fitted with a scale inhibitor, particularly given the limestone origin of some supply components, and annual servicing is advisable. Washing-up liquid performs well at standard quantities, though a small increase in detergent may be needed for heavily soiled items. Taps and shower heads show light limescale deposits within a few weeks; a regular wipe with white vinegar solution keeps surfaces clean and extends the life of fittings.