Manchester Water Hardness & Quality Report (2026)

Manchester, New Hampshire — the largest city in New England north of Boston — draws its municipal water supply from Lake Massabesic — a large natural lake in Auburn and Manchester Township, southeastern New Hampshire — operated by the Manchester Water Works. Lake Massabesic is the primary drinking water reservoir for Manchester, with a protected watershed managed for water quality across Rockingham County. Water is treated at the Lake Massabesic Water Treatment Plant before distribution throughout the Manchester metropolitan area. Water hardness measures 53 mg/L — classified as moderately soft.

Manchester's moderately soft supply reflects the New Hampshire Granite Province geology of the Lake Massabesic watershed. The Lake Massabesic watershed drains terrain underlain by the Concord Granite (Devonian–Mississippian biotite granite) and the Devonian Conway Formation (quartz-rich alkali feldspar granite) — two major New Hampshire granite plutons of the New England Appalachian Granite Province. These granitic rocks, intruded into the Precambrian–Paleozoic Merrimack Group schist and quartzite basement, are composed almost entirely of silica, alkali feldspars, and mica — minerals essentially free of soluble calcium carbonate. New Hampshire's cool, wet climate and the lake's forested protected watershed ensure consistently soft finished supply.

With hardness at 53 mg/L, Manchester residents experience minimal scale challenges in household use. Faucet aerators and showerheads rarely need descaling. Soap lathers well. Dishwashers produce clean glassware with minimal rinse-aid. Hot water systems remain largely scale-free. Manchester Water Works consistently delivers water meeting all New Hampshire DES and EPA Safe Drinking Water Act requirements.