Unsafe levels of lead have been found in the drinking water from nearly 10 percent of the faucets tested in city schools. Nearly every school tested had at least one faucet with tainted water, the result of old pipes and plumbing fixtures. NY1's Lindsey Christ filed the following report.

NY1 has learned that there are elevated levels of lead in the water in at least 750 school buildings.

"We're immediately addressing those particular fixtures, taking them offline, and students won't be able to drink from those fountains or fixtures until we've gotten negative test results," said Deputy Schools Chancellor Elizabeth Rose.

The city is re-testing all 1,500 school buildings after the New York Times reported that pipes in schools were routinely flushed for two hours before testing, a practice that can mask high levels of lead and is now banned by the state.

The city Education Department won't say exactly how many of those school buildings have been re-tested, but NY1 has learned that an overwhelming majority of those that have been inspected again came back with unsafe lead levels in water from at least one faucet.

6,337 fixtures in schools have been turned off after registering elevated lead levels, more than 8 percent of those tested. 

The city says the lead is not in the water supply but comes from pipes and faucets in the buildings. 

Lead poisoning can damage organs and the nervous system and cause developmental delays. The Environmental Protection Agency says any testing result higher than 15 parts per billion must be addressed.  

"Any result over 15 parts per billion, we are remediating. We're treating them all equally," Rose said. 

At NEST+m on the Lower East Side, the water from one faucet had a lead concentration of 1,140 parts per billion. At McKinley Junior High School in Dyker Heights, Brooklyn, a reading of 577 parts per billion was found.

At some schools, lead is in just a few of the fixtures that might have been used for drinking or cooking. But at others, like IS 27 on Staten Island, water from more than a third of the faucets had unacceptably high levels of lead. 

Education officials say there has never been a known case of lead poisoning traced to the water in city schools.