Westmont Water Hardness & Quality Report (2026)

Westmont, Illinois, in DuPage County in the western Chicago suburbs, receives its municipal water from Illinois American Water through the DuPage Water Commission infrastructure, which delivers a combination of treated Lake Michigan water purchased from the City of Chicago and supplementary groundwater from the Silurian Dolomite Aquifer underlying DuPage County. DuPage County communities draw Lake Michigan water through a major transmission system built in the 1960s–70s to replace diminishing deep well supplies, but most retain some groundwater blending for peak demand and distribution pressure purposes.

The very hard 197 mg/L hardness — notably harder than pure Lake Michigan water typically reads at 140–160 mg/L — confirms significant groundwater blending in Westmont's supply. DuPage County's local aquifer is the Silurian Niagara Dolomite, an ancient reef-derived carbonate formation that produces exceptionally hard water when tapped. Wells drawing from the Niagara Dolomite in DuPage routinely produce water in the 300–400 mg/L range, and blending with the 140-160 mg/L Lake Michigan supply elevates the finished water to the very hard range that Westmont residents experience.

At 197 mg/L, Westmont has very hard water with significant mineral scaling throughout all home systems. White scale builds rapidly in kettles and coffee machines, dishwashers leave persistent mineral film on all glassware, and bathroom fixtures develop calcium deposits that require regular cleaning. Water heater elements should be inspected annually. Descaling appliances every six to eight weeks is the practical cadence for this hardness level, and a whole-house water softener is a worthwhile investment for Westmont homeowners seeking to eliminate scaling throughout plumbing and extend appliance life. The PFAS level of 6.9 ppt warrants use of a certified filter for drinking water.