Mains water in Greater London (England) is supplied by Thames Water (predominant); SES Water (south); Affinity Water (NW/N); Essex & Suffolk Water (far NE); typical hardness: Very hard, ~302 mg/l CaCO3 (Thames). Water quality is regulated by the Environment Agency · Ofwat · Drinking Water Inspectorate.
Sources: Thames Water (predominant); SES Water (south); Affinity Water (NW/N); Essex & Suffolk Water (far NE)