Solihull Water Hardness & Quality Report (2026)

Solihull, the prosperous Metropolitan Borough in the southern West Midlands, is supplied by Severn Trent Water drawing from the same Welsh upland infrastructure that serves Birmingham. The primary source is the Elan Valley Reservoir system in Radnorshire — six linked reservoirs in the mid-Wales uplands conveying water by gravity aqueduct to Frankley Water Treatment Works in Worcestershire, then distributed through the West Midlands network. However, Solihull's position on the south-eastern edge of the conurbation means its supply incorporates a greater proportion of locally abstracted groundwater from the Triassic Sherwood Sandstone (Bunter Sandstone) aquifer beneath the Warwickshire–Staffordshire border than central Birmingham receives, raising the hardness somewhat above the pure Elan Valley value. Water is treated and distributed through Severn Trent's West Midlands network.

Solihull's hardness of 170 mg/L (11.9°Clark) — noticeably higher than Birmingham's 60–80 mg/L — reflects the increased Triassic Bunter Sandstone groundwater blend in the south-east West Midlands zone. The Sherwood Sandstone aquifer beneath Warwickshire and east Staffordshire is a Triassic Permo-Triassic formation whose groundwater acquires moderate calcium and magnesium from percolation through the sandstone and its interstitial mineral cements. This is blended with very soft Elan Valley supply, but the higher sandstone proportion in the Solihull distribution zone results in a moderately hard supply. The Drinking Water Inspectorate (DWI) classifies this supply as moderately hard.

Limescale requires regular household attention in Solihull. At 170 mg/L, limescale forms in kettles over three to four weeks and monthly descaling is advisable. Combi-boiler heat exchangers accumulate limescale deposits steadily — annual servicing with a limescale check and an in-line scale inhibitor are recommended. Showerheads, taps, and glass shower screens develop consistent deposits. Washing-up liquid lathers moderately. Adding Calgon monthly to the washing machine and maintaining a regular descaling routine is standard maintenance practice for Solihull homes.