Three sample types were taken from sites around the Greater Chicago metropolitan area including untreated Lake Michigan source water (red circle), water filtration plant (WFP)-treated pre-distribution water (green “x”), and post-distribution residential tapwater (blue triangle). Untreated intake and WFP-treated water was sampled at two WFPs in East Chicago, IN, one WFP in North Chicago, IL and one WFP in South Chicago. Residental post-distribution tapwater samples representing the North (n = 14) and South Chicago (n = 16) WFPs distribution areas were also sampled.