Chicago, the epicenter of brain-damaging lead hazards in the United States, is borrowing $336 million from the federal government to replace thousands of water pipes made of the toxic metal.

The low-interest loan announced Friday by the U.S. Environmental Protection Agency comes after decades of denials from city officials that Chicago suffers a widespread lead-in-water problem.

Money provided by the EPA is intended to replace 30,000 of the roughly 400,000 lead pipes known as service lines connecting homes and two-flats to the municipal water system.

[ A decade into the work, Chicago is finally taking out toxic lead pipes when it replaces water mains ]

There are more service lines made of lead in Chicago than any other American city, largely because clout-heavy unions ensured local ordinances required pipes made of the toxic metal until Congress banned their use in 1986.

A 2013 federal study of Chicago homes found that disturbing lead service lines can expose people to alarming concentrations of the brain-damaging metal.

Yet during the past decade the city borrowed more than $400 million to replace aging, sometimes leaking water mains and doubled the cost of water to pay for the work.

On each of the 792 miles dug up, crews hired by the Department of Water Management connected new cast-iron water mains to old lead pipes.

The federal loan announced Friday will pay to dig up some of those streets again to replace lead service lines.