As residents of Flint, Michigan, continue to live without drinkable water flowing from their pipes, a new round of testing found elevated lead levels in the water of public schools.

According to a report published by the Michigan Department of Environmental Quality, the approximate 4,500 children enrolled in the Flint Community Schools (FSC), the city’s public school system, attend class in buildings with potentially contaminated water. The latest round of water sample tests, reports MLive, “showed at least one instance of water with at least 15 parts per billion of lead in each of the 10 buildings [tested].” Doyle Ryder Elementary School, with a majority Black student population of 388 pre-K through sixth graders, had three samples that registered more than 100 ppb of lead—a result that is more than six times the federal action limit of 15 ppb. Overall, lead of varying amounts was detected in 44.5 percent of the samples tested throughout the school district, and 4 percent were over the federal action limit.

The state-sponsored testing is the final round of data gathering before a decision is made by Michigan officials as to whether the state will continue to provide free bottled water for Flint residents. Per MLive:

FSC has its own agreement with private companies, including Walmart, to supply bottled water to students until at least the end of the current school year.

But after that, students will be in the same position as residents throughout the city—waiting for the state to finish its review of the overall quality of Flint water before making a decision on future bottled water funding.

The state currently spends $22,000 per day on bottled water for the city’s residents—56.6 percent of whom are Black, with 41.2 percent living below the poverty line.

The water crisis was prompted by an April 2014 decision by the city to switch Flint’s water source from the Great Lakes Water Authority to the Flint River. It has been linked to elevated lead levels in children’s blood, outbreaks on Legionnaire’s disease, as well as a decrease in fertility and an increase in infant deaths. Four years after the crisis began, the city still lacks water that is safe to consume directly from the tap. Flint Mayor Karen Weaver has said bottled water should be supplied to residents until all lead and galvanized service lines are removed.

Last month, the U.S. Environmental Protection Agency (EPA) awarded a $100 million grant to the Michigan Department of Environmental Quality to fund drinking water infrastructure upgrades in Flint.

“We are excited and very grateful to receive these much needed funds,” said Weaver in a statement at the time of the announcement. “The City of Flint being awarded a grant of this magnitude in such a critical time of need will be a huge benefit. As we prepare to start the next phase of the FAST Start pipe replacement program, these funds will give us what we need to reach our goal of replacing 6,000 pipes this year and make other needed infrastructure improvements.”

It has been estimated that it could take until 2020 to replace all of the pipes.