The Flint river water is acidic, and leaches lead from wherever it can find it, including solder joints and service lines. They have been testing in residential taps and finding levels as high as 13K ppb. Maximum allowed is 5 ppb. Some small children are exhibiting signs of early stage lead poisoning.
Now that the acidic water has cleaned off the scale in many of the lines, lead has been re-deposited downstream, in galvanized and copper pipes, where it remains vulnerable to further leaching by the Detroit water.
Now that the acidic water has cleaned off the scale in many of the lines, lead has been re-deposited downstream, in galvanized and copper pipes, where it remains vulnerable to further leaching by the Detroit water.