Spatial and Demographic Trends in Lead Levels: The Case of Chicago’s Water System

Contaminants, such as lead, in water systems pose significant public health risks. Despite growing public awareness, the presence of lead service lines remains a concern in water systems. Consequently, there is a need to ascertain spatial and demographic trends in lead contamination to identify regional areas to monitor and to inform outreach campaigns. Leveraging lead water quality data collected in Chicago, we use Poisson regression analysis to identify the zip code-level demographic drivers of high lead levels. Our model showed that the percentage of Black residents and the percentage of buildings built before 1980 were significantly associated with the percentage of samples with more than 15 ppb of lead, the EPA standard. Such trends shed light on underlying issues that may contribute to lead contamination, such as historic inequities in the built environment. These findings will assist decision-makers in prioritizing capital projects and educational campaigns, ultimately improving water services.