Menlo Park Water Hardness & Quality Report (2026)

Menlo Park, California, in San Mateo County — a major north San Mateo County Silicon Valley community (Menlo Park is at the heart of Silicon Valley — home of Sand Hill Road, the most concentrated venture capital corridor in the world, with dozens of major VC firms funding technology startups; Meta/Facebook's global headquarters are in Menlo Park, making it one of the most economically significant small cities in the United States), a diverse San Mateo County community with a significant Chinese-American, South Asian-American, and technology executive and venture capitalist population, adjacent to Palo Alto and Stanford University (Stanford University's campus is directly adjacent to Menlo Park's boundaries — the two communities are essentially contiguous), and a highly affluent San Francisco Bay Peninsula community — draws its municipal water supply via California Water Service (SFPUC). Water hardness in Menlo Park measures 69 mg/L — classified as moderately soft.

Menlo Park's moderate softness reflects the SFPUC Hetch Hetchy supply dominance. The SFPUC Hetch Hetchy supply (O'Shaughnessy Dam, Sierra Nevada, Tuolumne River — draining calcareous-poor Sierra Nevada granite) is the primary Menlo Park supply (supplemented minimally by local Peninsula reservoir water). The dominant Hetch Hetchy soft supply produces the moderate 69 mg/L.

With hardness at 69 mg/L, Menlo Park residents enjoy moderately soft water. California Water Service consistently delivers water meeting all California DDW and EPA Safe Drinking Water Act requirements.