Hawaii will test the drinking water at 72 elementary schools for lead in the second phase of a project that began last year, officials said Monday.

Testing is due to begin on May 27 – a day after the school year ends – and will continue through September, according to a press release from the state Department of Education.

The effort is part of a joint project between the DOE and the state Department of Health to examine drinking water, especially in schools for young children. It is also part of a nationwide project established by federal law.

Results from tests conducted last year in 106 public elementary schools in Hawaii found that 89 of them had elevated concentrations of lead, or levels exceeding 15 parts per billion, in at least one faucet.

The Lead and Copper Rule action level for lead under the U.S. Safe Drinking Water Act is 15 parts per billion.

Schools that produce water samples showing lead levels exceeding the federal safety standard will have to shut off their water taps within 24 hours or by the next school day, according to the DOE.

“Testing in the first phase of this project allowed us to take action to identify and remove from service fixtures that exceeded the lead action level,” DOH toxicologist Diana Felton said in the news release. “The second phase of this project will allow us to complete sampling at elementary schools across the state to ensure that we are providing a safe learning environment for all keiki.”

The education department stressed that while drinking water is a potential source of lead poisoning, most children are exposed to the toxic substance at home.

“Long-term exposure to lead has greater consequences for younger keiki and can result in problems with learning, attention, and behavior, among other health problems,” interim superintendent Keith Hayashi was quoted as saying.

Last month, lead was detected in water samples from Pearl Harbor Kai Elementary School and Moanalua Preschool/Kama‘aina Kids in separate testing as part of a monitoring agreement stemming from the military’s fuel contamination crisis.