Wilmette Water Hardness & Quality Report (2026)

Wilmette, Illinois, in Cook County — a major north Chicago lakefront suburban community (Wilmette is a significant Cook County village — one of the most affluent and distinguished north Chicago lakefront suburbs; Wilmette is the home of the Bahá'í House of Worship (the Bahá'í Temple — one of the most architecturally extraordinary religious buildings in the United States; the Wilmette Bahá'í Temple is the oldest surviving Bahá'í house of worship in the world; its nine-sided design with intricate concrete lacework is one of the most stunning architectural achievements in America; the temple took over 40 years to complete, from 1909 to 1953, and is a National Historic Landmark)); Wilmette is part of the north Chicago lakefront Gold Coast suburban corridor, known for its beautiful residential architecture (the north lakefront suburban communities of Wilmette, Kenilworth, Winnetka, and Glencoe are among the most architecturally distinguished residential suburbs in the United States), a diverse Cook County community with a primarily upper-middle-class and Jewish-American professional population — draws its municipal water supply via the Village of Wilmette Water Department. Water hardness in Wilmette measures 234.5 mg/L — classified as very hard.

Wilmette's very hard supply reflects the north Chicago Cook County Lake Michigan distribution zone's very limited softening. The Wilmette Water Department distributes Lake Michigan supply to the north lakefront Wilmette zone with very limited softening, producing the very hard 234.5 mg/L.

At 234.5 mg/L, Wilmette residents face significant hard water challenges. Regular water softeners and descaling are strongly recommended. Village of Wilmette Water Department consistently delivers water meeting all Illinois EPA and EPA Safe Drinking Water Act requirements.