All Chicago Public Schools will be tested for lead in its water supply after Tanner Elementary School tested positive while part of a pilot program. CPS Chief Executive Officer Forrest Claypool said that 31 of 32 schools passed a pilot testing program launched after concerns stemming from lead poisoning in Flint, Michigan.

According to DNA Info, 25 of the schools had no lead whatsoever in the water. Six others met federal standards for the presence of lead in water.

Claypool cited an “abundance of caution” as the reason for expanding testing to all schools. All of Tanner Elementary school’s water fountains and faucets have been shut down after three fountains tested positive for lead. The school is located on the city’s South Side.

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