Noe Valley Water Hardness & Quality Report (2026)

Noe Valley, California, in the City and County of San Francisco — one of San Francisco's sunniest and most coveted residential neighborhoods, sheltered from coastal fog by Twin Peaks and known for its Victorian streetscapes and 24th Street boutique corridor — receives its municipal water from the San Francisco Public Utilities Commission (SFPUC), which draws from the Hetch Hetchy Reservoir (O'Shaughnessy Dam on the Tuolumne River in Yosemite National Park), supplemented by Crystal Springs Reservoir (San Mateo watershed) and local Westside Groundwater Basin wells during drought or maintenance periods. SFPUC delivers water to all San Francisco neighborhoods through the city's aging distribution network.

The moderately hard 186 mg/L hardness and elevated TDS of 587.9 mg/L are substantially above the typical SFPUC Hetch Hetchy baseline (~25–50 mg/L hardness), indicating significant mineral contributions beyond the soft Tuolumne River source. The Hetch Hetchy supply drains the Sierra Nevada granodiorite and metamorphic basement terrain with essentially no carbonate — one of the softest municipal supplies in the country. The elevated Noe Valley values likely reflect contributions from the Westside Groundwater Basin (the Colma Formation Pleistocene marine deposits beneath the Sunset District) with higher mineral content, as well as distribution system mineral accumulation in the San Francisco mid-century pipe network serving the hill neighborhoods.

At 186 mg/L, Noe Valley's supply is moderately hard — significantly different from the soft water most San Francisco neighborhoods receive on the direct Hetch Hetchy feed. Scale builds in kettles and coffee machines within weeks to months, the dishwasher benefits from rinse aid, and shower glass develops calcium film. Quarterly descaling of heating appliances is the practical schedule. The PFAS level of 7.4 ppt warrants a certified drinking water filter — SFPUC's long-distance pipeline from Hetch Hetchy crosses the San Joaquin Valley, where agricultural PFAS contributes to the regional water supply baseline.