Portsmouth Water Hardness & Quality Report (2026)

The City of Portsmouth Water Division serves approximately 21,000 residents in Portsmouth, New Hampshire, located in Rockingham County along the Seacoast Region. Water is sourced from surface water via the North and Little North Rivers through the Peverly Brook intake, and from groundwater wells in the Massabesic Lake area. Treatment occurs at the Peverly Hill Road Water Treatment Plant, where filtration, disinfection, and corrosion control are applied before distribution through the municipal system covering the city and some adjacent areas.

The supply originates in the Piscataqua River watershed, encompassing forested uplands underlain by Ordovician and Devonian granitic and metamorphic bedrock formations—including Kittery Quartzite and Eliot Formation schists. These non-carbonate rocks, overlain by glacial till and outwash deposits, form fractured bedrock aquifers with naturally low mineralization. The absence of limestone or dolomite formations prevents significant uptake of hardness-causing ions during infiltration, producing characteristically soft water typical of New England granitic terrains.

As soft water, Portsmouth's supply produces minimal scale buildup, sparing water heaters, dishwashers, and washing machines from heavy limescale accumulation. Faucets and fixtures experience little staining, and soap lathers efficiently without excess detergent. Routine descaling of coffee makers or kettles suffices; a water softener is not recommended, as it could strip beneficial minerals or worsen corrosion risks. PFAS levels have been detected above health guidelines in past sampling, prompting granular activated carbon treatment upgrades; the utility otherwise maintains compliance with EPA standards across over 90 monitored contaminants.