Park Forest Water Hardness & Quality Report (2026)

Park Forest, Illinois, in Cook County — a historic south suburban Cook County planned community developed after World War II as one of America's early purpose-built postwar suburbs, designed by Elbert Peets and Philip Will Jr. as a model democratic mixed-income community — receives its municipal water from Illinois American Water or the Village of Park Forest Utilities, which draws from the Lake Michigan supply through the south metropolitan Chicago transmission system or from local Calumet corridor sources. Park Forest is served through the south Cook County regional water distribution network.

The moderately hard 157.5 mg/L hardness and TDS of 295.4 mg/L reflect the south Cook County supply zone's intermediate character between the very hard local Calumet dolomite platform groundwater (~260+ mg/L) and the somewhat softer Lake Michigan supply. The south suburban Chicago distribution network in Cook County blends Lake Michigan water (after treatment softening) with local supply in a network where distribution zone position and infrastructure age significantly affect finished water hardness. Park Forest's supply zone produces a moderately hard blend reflecting the south metropolitan Chicago distribution character.

At 157.5 mg/L, Park Forest's water is moderately hard — scale builds in kettles and appliances over months, dishwashers benefit from rinse aid, and bathroom fixtures develop calcium deposits. Quarterly descaling of heating appliances is appropriate. The PFAS level of 5.6 ppt warrants a certified drinking water filter — the south Cook County industrial corridor, the Matteson-Park Forest area's transit-industrial heritage, and the broader south Chicago metropolitan PFAS background from the Calumet River manufacturing corridor contribute to the Park Forest supply area PFAS profile.