Royston Water Hardness & Quality Report (2026)

Affinity Water supplies Royston, a market town in south Hertfordshire straddling the ancient Icknield Way at the Hertfordshire–Cambridgeshire border, from the deeply confined Hertfordshire–Cambridgeshire Chalk aquifer beneath the chalk plateau around Royston Heath, treated at regional south Hertfordshire works. At 316.5 mg/L (22.2°Clark) and a TDS of 948.3 mg/L, Royston's water is extremely hard — reflecting the near-saturated confined chalk aquifer of the Chiltern–Cambridgeshire chalk belt, where groundwater buried beneath glacial drift achieves maximum calcium bicarbonate saturation.

The Royston Heath chalk plateau sits on the southern face of the East Anglian chalk — the same Cretaceous chalk formation that underlies the Chilterns and the Cambridgeshire Fens. Beneath the plateau, Anglian glacial deposits — boulder clay and glaciofluvial gravels — confine the chalk as a pressurised aquifer with long residence times. This confinement allows calcium carbonate dissolution to continue until near-equilibrium saturation, producing TDS approaching 950 mg/L and hardness of 316.5 mg/L — placing Royston among the most extreme chalk aquifer supply zones in England, comparable to the confined chalk of Essex and north Kent.

Limescale is an extreme and relentless domestic challenge in Royston. Kettles must be descaled every one to two weeks to prevent rapid element destruction. Combi-boilers face a very high risk of premature failure without a properly fitted, annually replaced scale inhibitor and regular professional servicing of the heat exchanger. Washing-up liquid requires substantially more product per wash to produce any useful lather. Taps, shower screens, and basin mixers must be descaled weekly to prevent permanent hard-water crust forming on all surfaces, and a whole-house water softener is strongly recommended to protect all appliances and plumbing from severe limescale damage.