Norwalk Water Hardness & Quality Report (2026)

First District Water Department (FDWD) supplies drinking water to over 88,000 residents in Norwalk, Connecticut, and surrounding areas in Fairfield County. The utility sources water from surface reservoirs including the Norwalk River Reservoir system and five groundwater wells. Treatment occurs at the Silvermine Treatment Plant for surface water, involving filtration, disinfection with chlorination, and corrosion control, while groundwater receives disinfection and blending before distribution through an extensive piped network serving urban neighborhoods from SoNo to East Norwalk.

The Norwalk River basin drains 64 square miles of suburban and forested land bordered by Long Island Sound. Underlying geology includes metamorphic and sedimentary rocks of the Berkshire Highlands transitioning to Triassic-Jurassic sedimentary basins, with Pleistocene glacial deposits forming productive stratified drift aquifers. The Cambrian-Ordovician Stockbridge Formation limestone contributes dissolved calcium and magnesium through fractured bedrock and karst features, imparting a moderately mineralised character — carbonate dissolution and cation exchange in glacial sands elevate mineral content, with state assessments noting contamination vulnerability.

Moderately hard water promotes limescale buildup in pipes, reducing water heater efficiency by up to 29% and shortening appliance lifespan, particularly affecting dishwashers, washing machines, and coffee makers. Spotting on glassware and dry skin are common complaints. Routine heater flushing, vinegar descaling of fixtures, and installing a whole-house softener are recommended to mitigate scaling and extend equipment life. Water maintains EPA compliance with pH typically neutral; proactive PFAS testing detected levels well below the 70 ppt Health Advisory. Notable detections include low trihalomethanes, chromium-6, and nitrates — all below MCLs but exceeding some health guidelines per third-party analyses.