One in 20 tap water tests performed for thousands of Chicago residents found lead, a neurotoxin, at or above US government limits, according to a Guardian analysis of a City of Chicago data trove.
And one-third had more lead than is permitted in bottled water.
This means that out of the 24,000 tests, approximately 1,000 homes had lead exceeding federal standards. Experts and locals say these results raise broader concerns, because there are an estimated 400,000 lead pipes supplying water to homes in the city, and the vast majority were not tested as part of the program.
Moreover, they say the city is not moving fast enough to eliminate the potential danger.