Romsey Water Hardness & Quality Report (2026)

Southern Water supplies Romsey, a historic market town in the Test Valley of Hampshire on the nationally celebrated chalk stream River Test. Supply is drawn from abstraction on the River Test itself and from Hampshire Chalk aquifer boreholes in the Test Valley, treated at Otterbourne and Test Valley works before distribution across south Hampshire. At 169 mg/L (11.9°Clark), Romsey's water is moderately hard — somewhat less hard than many Hampshire towns — reflecting the test catchment's blend of chalk spring inputs with dilution from the upper Test's Greensand and Chalk Marl tributaries that reduce overall hardness relative to the purest deep-chalk sources.

The River Test is England's most celebrated chalk stream, emerging as crystal-clear chalk springs near Ashe and Overton in north Hampshire. As the Test flows southward to Romsey, it collects tributaries draining a mix of pure Upper Cretaceous Chalk and Upper Greensand formations of the Test Valley escarpment, with the greensand component diluting the chalk hardness slightly. The result is moderately hard rather than very hard water at Romsey — still distinctively chalk in character but at a lower hardness level than the confined deep-chalk boreholes further east in Hampshire.

At 169 mg/L, limescale is a noticeable domestic concern in Romsey. Kettles benefit from descaling every four to six weeks to maintain element efficiency. The combi-boiler should be fitted with a scale inhibitor and serviced annually. Washing-up liquid performs adequately at normal quantities. Taps and shower heads develop moderate limescale deposits over a few weeks; a monthly wipe with white vinegar or a mild descaling product keeps fittings clean. The moderately hard chalk-stream water of the Test Valley is characteristic of Romsey's distinctive riparian chalk landscape.