Roslindale Water Hardness & Quality Report (2026)

The Boston Water and Sewer Commission (BWSC) provides water services to Roslindale, MA, serving over 600,000 residents across approximately 75 square miles of Boston. Water is supplied wholesale by the Massachusetts Water Resources Authority (MWRA), sourced primarily from the Quabbin Reservoir (95% average) and Wachusett Reservoir, with occasional blending from the Connecticut River via the Cobble Mountain Reservoir. Treatment occurs at the John J. Carroll Water Treatment Plant in Marlborough, MA, employing ozonation, chloramination, and UV disinfection before distribution through BWSC pipes.

The Quabbin and Wachusett Reservoirs lie within protected forested watersheds in the Swift River and Wachusett Reservoir drainages, part of the larger Connecticut River Basin. Underlying geology features hard, non-soluble igneous and metamorphic rocks — granite, gneiss, and schist from Paleozoic orogenic events — with glacial overburden limiting mineral dissolution. Absent significant limestone or dolomite formations, the supply remains very soft, shaped by short reservoir residence times and evergreen forest filtration.

The soft supply means scale buildup is minimal, with limited effects on water heaters, dishwashers, and coffee makers; slight spots on glassware may occur over time. Routine flushing of fixtures and vinegar descaling suffice for maintenance; a water softener is generally not recommended, as it could over-demineralize the water. MWRA/BWSC water maintains pH 8.5–9.5 for corrosion control; no PFAS detections above advisory levels were reported in the 2024 CCR, and all parameters meet EPA Safe Drinking Water Act standards.