Madison Water Hardness & Quality Report (2026)

Madison, Connecticut, in South Central Connecticut — a coastal Connecticut town adjacent to Clinton and Guilford on Long Island Sound, one of the most affluent shoreline communities on the Connecticut Shore — receives its municipal water from the South Central Connecticut Regional Water Authority (SCCRWA) or the Madison Water Division, drawing from local reservoirs in the Hammonasset River watershed.

The very soft 38.5 mg/L hardness and very low TDS of 69.8 mg/L reflect the Connecticut shoreline's crystalline bedrock watershed character. Madison's reservoirs drain the Connecticut Coastal Plain — terrain underlain by Precambrian crystalline gneiss and schist of the Bronson Hill Terrane and the New England Upland (insoluble silicate), with minor Triassic Hartford Basin sandstone contact. The extremely soft supply is characteristic of the southern New England crystalline rock watershed reservoirs — among the softest in any eastern metropolitan region.

At 38.5 mg/L, Madison's water is very soft — essentially no scale forms, soap lathers abundantly, and appliances achieve maximum lifespan. Annual descaling is sufficient. The PFAS level of 6.6 ppt warrants a certified drinking water filter — the Connecticut Shore PFAS industrial background (Sikorsky Aircraft (Stratford, CT) legacy, United Technologies legacy in the Lower Connecticut Valley), and the Long Island Sound PFAS airshed deposition contribute to Madison's elevated readings despite its pure source water.