Marc Edwards, the man responsible for blowing the whistle on the Flint water crisis, said that the only way to protect school children against lead contamination in drinking water is to test virtually every fountain or sink they might use during the day regularly. NBC survey the 20 biggest cities in the U.S. and found very few to be meeting this standard.

The survey showed that Los Angeles had not done district-wide testing in years. On the other hand, Chicago had no record of testing its 600+ schools until they recently launched a program that has not even seen results—despite having at least twice the national average lead poisoning rate.

It must be noted that schools are not required by law to test what comes out of their taps for lead. Edwards stresses that water may not be lead-free just because it left the city treatment plant that way and although most schools aren't connected to pure lead service line, any plumbing installed before the 2014 lead-free law could contain lead:

The link between lead and aging infrastructure means that one-time testing isn't enough, Edwards said. A school that was deemed safe a decade ago could yield elevated lead today as pipes corrode and disgorge loose fragments into the water, he said.

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