Southbury Water Hardness & Quality Report (2026)

Southbury, Connecticut, in the Naugatuck Valley Planning Region — a historic Connecticut town on the Housatonic River at the confluence with the Pomperaug River, a mixed residential and agricultural community in western Connecticut — receives its municipal water from Aquarion Water Company or the South Central Connecticut Regional Water Authority, which draws from Lake Zoar (impoundment on the Housatonic River in Oxford-Monroe, near Southbury) through the western Connecticut water supply system.

The very soft 41.5 mg/L hardness and low TDS of 76.9 mg/L reflect the Housatonic River watershed's Berkshire Hills crystalline geology. The Housatonic River drains the Berkshire Hills of Massachusetts and Connecticut — terrain dominated by Precambrian Grenville-age gneiss and Cambrian Stockbridge Marble (metamorphic limestone), Taconic phyllite and schist, and the Triassic Hartford Basin fringe. While the Stockbridge Marble adds minor calcium carbonate, the predominant crystalline Berkshire terrain produces soft runoff, and Lake Zoar's large catchment area dilutes the hard marble contribution, producing the very soft Southbury supply.

At 41.5 mg/L, Southbury's water is very soft — excellent for household use. Scale forms very slowly, soap lathers richly, and appliances maintain excellent efficiency. Annual descaling is more than sufficient. The PFAS level of 6.8 ppt warrants a certified drinking water filter — the Shelton industrial corridor (Housatonic valley — former copper wire manufacturing, Sikorsky Aircraft Stratford downstream), the Naugatuck Valley historic brass and copper mill complex, and the western Connecticut industrial PFAS legacy contribute to Southbury's elevated PFAS despite the clean soft supply.