Norwich Water Hardness & Quality Report (2026)

Norwich, Connecticut, in New London County — the 'Rose of New England' (Norwich's 19th-century nickname), a historic colonial Connecticut city at the confluence of the Shetucket and Yantic rivers forming the Thames River, birthplace of Benedict Arnold (the American Revolution general and traitor — born in Norwich in 1741), home of the Mohegan Sun (one of the largest casinos in the United States, owned by the Mohegan Tribe — a major federally recognized Connecticut tribe whose ancestral homeland includes the Norwich area), and a diverse southeastern Connecticut community with significant Puerto Rican and Guatemalan-American populations — draws its municipal water supply from Shetucket River reservoirs via the Norwich Public Utilities (NPU). Water hardness in Norwich measures 98.5 mg/L — classified as moderately soft.

Norwich's moderate softness reflects the eastern Connecticut Thames–Shetucket watershed's calcareous-poor crystalline geology. The Shetucket River watershed at Norwich drains: the Connecticut Eastern Upland (Precambrian–Paleozoic calcareous-poor gneiss and schist — the Avalon terrane of eastern Connecticut and the easternmost Connecticut crystalline core, calcareous-poor); and Glastonbury Gneiss and Scottish–Windham metamorphic units (calcareous-poor crystalline terrain). The NPU treatment of the calcareous-poor crystalline watershed produces the moderate 98.5 mg/L — softer than the Connecticut Valley cities using carbonate watershed supplies.

With hardness at 98.5 mg/L, Norwich residents enjoy moderately soft water. Norwich Public Utilities consistently delivers water meeting all Connecticut DEEP and EPA Safe Drinking Water Act requirements.