Harwich Water Hardness & Quality Report (2026)

Essex & Suffolk Water, part of the Anglian Water group, supplies Harwich on the Essex coast. The town's water is sourced primarily from the River Stour estuary catchment and groundwater from the Chalk aquifer of north Essex, treated at Langham and Abberton Water Treatment Works before distribution across the Tendring peninsula to Harwich. The Chalk aquifer of north Essex contributes highly mineralised groundwater, and the Stour itself drains chalk and boulder clay country upstream in Suffolk and Cambridgeshire. At 243.5 mg/L (17.1°Clark), Harwich's water reflects this chalk-dominated supply.

The Upper Cretaceous Chalk underlies much of north Essex and south Suffolk at relatively shallow depth, and groundwater abstracted from boreholes in this aquifer has high calcium bicarbonate content developed through extended contact with the porous chalk matrix. The River Stour, rising in the chalk-influenced farmland of the Suffolk and Essex borders, carries dissolved calcium throughout its catchment. Glacial boulder clay deposits overlying the chalk also contain calcium carbonate from eroded limestone, contributing further hardness to both surface water and shallow groundwater inputs across the Tendring peninsula.

Limescale is a persistent daily concern in Harwich. Kettles should be descaled monthly, with fortnightly descaling worthwhile in households that use the kettle frequently. The combi-boiler benefits from a fitted scale inhibitor to protect the heat exchanger, and an annual service to check for calcium deposits is advisable. Washing-up liquid does not lather as readily as in softer-water areas; slightly more product is typically needed per wash. Taps and shower heads develop visible white limescale deposits within a week or two and benefit from regular treatment with white vinegar or a proprietary descaler — fortnightly at minimum — to prevent permanent hard-water staining and damage to fittings.