Old Saybrook Water Hardness & Quality Report (2026)

Old Saybrook, Connecticut, in the Lower Connecticut River Valley Planning Region — a southeast Connecticut shoreline town adjacent to Clinton and Essex at the mouth of the Connecticut River — receives its water from the Old Saybrook Water Division, drawing from local reservoirs through the southeast Connecticut distribution.

The extremely soft 15.5 mg/L hardness and very low TDS of 23.3 mg/L reflect the Lower Connecticut River Valley supply's extremely soft coastal character — the Precambrian Avalon Terrane and Jurassic Portland Formation are largely insoluble metamorphic and sandstone formations; Old Saybrook's coastal reservoir supply draws from very shallow glaciated terrain with minimal contact time with any calcareous formations (compare Clinton CT: 14/21 in Lower Connecticut River Valley comparable; Essex CT: 16/25 in Lower Connecticut River Valley comparable; Old Saybrook consistent very soft from the same Lower Connecticut River Valley Connecticut River Precambrian insoluble supply). The Connecticut River estuary watershed — Precambrian Avalon Terrane (insoluble — primary dilutant), Jurassic Portland Formation (insoluble — secondary dilutant), and Quaternary Connecticut coastal glacial till (slightly calcareous — minimal TDS).

At 15.5 mg/L with TDS 23, Old Saybrook's water is extremely soft — virtually no scale. Very soft water can be noticeably corrosive — consider a pH neutralizer or monitor for copper and lead staining. The PFAS level of 4.6 ppt is moderate — a certified drinking water filter provides added protection. Review the Old Saybrook Water Division's annual water quality report.