Nearly 20 percent of the water fountains in Chicago parks tested positive for excess levels of lead in the water and have been shut down by the Chicago Park District.

Hundreds of drinking fountains in Chicago parks have been shut off after testing revealed high levels of lead in the water.CBS Chicago

Of the 1,891 outdoor fountains in city parks, 445 exceeded the U.S. Environmental Protection Agency's (EPA) action level of 15 parts per billion. Another 14 of 544 indoor water fountains were contaminated as well. However, the EPA's Lead and Copper Rule refers primarily to municipal water systems, not single source supplies. The rule requires that action be taken if more than 10 percent of the taps tested exceed the 15 parts per billion standard.

The U.S. Food and Drug Administration (FDA) regulates bottled water, and has set a standard of 5 parts per billion. The difference is designed to account for the fact that bottled water does not flow through lead pipes. In cases where it is sourced from municipal water supplies, it must be run through one of several filtration processes in order to be labeled as "purified." If the Chicago Park District used the FDA standard, an additional 250 fountains would have to be shut down.

Exposure to high levels of lead for children can lead to reduced cognitive function, lower IQ scores, behavior, learning and hearing problems as well as anemia and slowed growth. Effects on pregnancy include premature birth and reduced growth of the fetus. Lead can be harmful to adults, including hypertension and reproductive issues. In Flint, Michigan, where the crisis of lead in water gained national attention, residents reported rashes and hair loss that may be linked to contaminated water.

On Tuesday, the American Civil Liberties Union (ACLU) of Michigan filed a class-action civil rights lawsuit against the Michigan Department of Education, Genesee County Intermediate School District and Flint Community Schools. The suit alleges ongoing violations of federal education laws and seeks screening and funding for special education services.

During the 2014-2015 school year, at the height of the water crisis, the suspension and expulsion rate for special education students in Flint Community Schools was more than five times higher than the rate for special education students in all Michigan school districts, according to a statement released by the ACLU of Michigan.

"All children can learn," said Kary Moss, executive director of ACLU of Michigan. "Universal, free public education is a cornerstone of our democracy and a basic civil right. But the rights of schoolchildren and their families are being violated every day in Flint. This lawsuit exposes what has gone wrong—including a dysfunctional funding structure—and demands clear and urgent remedies to make it right."

Last week, tests showed excessive levels of lead in 30 of 180 parochial schools in the Archdiocese of Chicago. Across the U.S., 18 million people drink water that violates the standards set forth in the Lead and Copper Rule. In Pennsylvania, 8.5 percent of children tested were found to have dangerously high levels of lead in their blood. Schools in Portland, Atlanta and Washington have been found with lead-contaminated water. In June, an investigation by The Guardian found 33 cities that had rigged their water tests.

Much of the problem can be traced to aging water pipes in cities and towns across the U.S. Some 6 to 7 million lead pipes bring water to schools, homes and hospitals in America. Replacing those lines carries a price tag of $30 billion.

But the cost of leaving those lead pipes in place is even higher, measured in the health of America's children and their families. In many of these tested locations, lead levels didn't just slightly exceed the standards: they exceeded them by multiples. In Chicago's parochial schools, some samples tested at 40 parts per billion. Flint schools measured as high as 2,800 parts per billion. In Avalon Park in Chicago, one fountain registered 1,800 parts per billion, while another measured 1,200.

As a Natural Resources Defense Council report put it, "No amount of exposure to lead is safe."