Durham Water Hardness & Quality Report (2026)

Durham, New Hampshire, in Strafford County — a Strafford County town adjacent to Lee and Newmarket on the Oyster River in southeast New Hampshire — receives its water from the Durham Water and Sewer Department, drawing from the Oyster River watershed through the southeast New Hampshire distribution.

The very soft 25 mg/L hardness and very low TDS of 42.9 mg/L reflect the Strafford County supply's very soft metamorphic-granite character — the Precambrian Rye Formation and Paleozoic Concord Granite are largely insoluble crystalline formations in the southeastern New Hampshire coastal upland, contributing minimal dissolved mineral content to the clean Oyster River supply (compare Lee NH: 23/39 in Strafford County comparable; Newmarket NH: 27/47 in Rockingham County comparable; Durham consistent very soft from the same Strafford County Oyster River Precambrian insoluble supply). The Oyster River watershed — Precambrian Rye Formation (insoluble — primary dilutant), Paleozoic Concord Granite (insoluble — secondary dilutant), and Quaternary southeastern NH glacial till (slightly calcareous — minimal TDS).

At 25 mg/L with TDS 43, Durham's water is very soft — virtually no scale buildup. Very soft water can be mildly corrosive — monitor for copper staining. The PFAS level of 4.4 ppt is moderate — a certified drinking water filter provides added protection. Review the Durham Water and Sewer Department's annual water quality report.