According to a News21 analysis, 44 states do not require schools to check their water for the presence of lead, and the federal government doesn’t, either. Only 6 states require mandatory lead testing: Illinois, Maryland, Minnesota, New Jersey, New York, and Virginia.
A 1986 amendment to the Safe Drinking Water Act banned the use of lead pipes for transporting water, as lead was found to leach from them. However, many schools still receive water through these pipes, as Congress did not require schools to replace them.
Today, Congress defines “lead-free” as a weighted average of 0.25% lead across the wetted surfaces of a pipe.
Schools are reluctant to fix lead problems due to the monetary cost, as well as their effects on public relations.
You can read more about this topic here: https://www.publicintegrity.org/2017/08/15/21076/schools-fail-lead-tests-while-many-states-don-t-require-testing-all
