Examining the Differences in Water Treatment Between Chicago and Evanston

Drinking water is a critical component of peoples' everyday lives, so it is critical that the quality of municipal tap water is accurately measured and adheres to contaminant limits. The U.S. Environmental Protection Agency (EPA) established the Lead and Copper Rule (LCR) in 1991 to reduce exposure to lead and copper in drinking water, which can cause numerous health impacts like cognitive defects and liver damage. However, proper measurement of lead concentration remains difficult, especially in cities like Chicago and Evanston where lead service lines are ubiquitous. The 2024 Lead and Copper Rule Improvements require sequential first- and fifth-liter samples. Our study collected water from households in Evanston and Chicago, who both draw water from Lake Michigan, but use different water treatment practices that are unknown to the public. Our study discusses the differences in concentrations of lead, copper, and other water contaminants taken through this revised sampling method. In our study, we identify significant differences in water quality between the two cities that are likely due to differences in water treatment practices, and discuss the implications of these results for optimal corrosion control strategies.