HARI SREENIVASAN, PBS ANCHOR:

Looking beyond the lead-tainted drinking water crisis in the city of Flint, Michigan, an Associated Press investigation of Environmental Protection Agency records has found nearly 1,400 water systems providing tap water to nearly 4 million Americans exceeded the acceptable lead level at least once between 2013 and 2015.

AP reporter Megan Hoyer co-wrote the story "Tainted at the Tap" and joins me now from Washington, D.C. How wide-ranging is this? Is this every part of the country geographically? Is it size of cities, big and small?