All Illinois schools and child-care centers will have to test drinking water for lead by 2018 under a new law signed today by Gov. Bruce Rauner.

The law requires schools built before 1987 to test by the end of this year and schools built after 1987 to test by the end of next year. Schools that have already had comprehensive testing performed on all fixtures like drinking fountains, classroom faucets and kitchen spigots within the past three years are exempt from the new law, but administrators have to submit those results to the Illinois Department of Public Health.

Until now, only schools that used well water were required to test the quality. Most suburban schools use water from Lake Michigan or the Fox River. Water suppliers are required to test for lead every three years, but that's in an effort to determine if the system is contaminated. Lead contamination in schools is more likely to be caused by the fixtures than the water itself, research has shown.

Lead contamination is particularly dangerous for children, as health experts say it can alter brain development. Studies have linked early childhood lead poisoning to learning disabilities and violent aggression later in life.

The law had stalled in Springfield because of concerns about testing and remediation costs as well as questions about who would be responsible for performing the tests. School and municipal leaders balked at language in a previous bill.

A compromise was reached late last month after a Daily Herald investigation revealed 15 percent of the 5,112 water samples taken from 319 suburban schools contained a measurable amount of lead. But 325 suburban schools had done no testing for lead in water.

The investigation showed lead testing could be done for as little as $15 per sample.

"Today is about our future, about making sure our students are not exposed to lead poisoning," Rauner said. "This shows what is possible when we work together. It is a step in protecting our children from the devastating effects of lead exposure."

The new law allows school districts to use tax revenue levied for student safety and legal issues to pay for testing and any potential remediation.

Under the new law, any sample that tests above 5 parts per billion will require school administrators to notify all parents or guardians. However, the law does not require schools to perform any immediate remediation. The U.S. Environmental Protection Agency recommends schools shut off service to drinking water outlets that show lead contamination of 20 parts per billion or higher. Health officials say there is no safe level of lead contamination.

The law also spells out how testing will be conducted. Many suburban schools in the Daily Herald analysis had to retest fixtures because initial sampling wasn't done correctly, skewing results.

The new law also mandates testing in all state-licensed child-care facilities.

In addition to the new lead testing law for schools, Barrington Hills Republican state Rep. David McSweeney championed a bipartisan effort to require the Illinois Environmental Protection Agency to publish a statewide water quality report that was issued recently. The effort was in response to another Daily Herald investigation of 172 suburban water systems in 89 communities that showed 70 percent of the systems reported some samples with varying levels of lead, but none that exceeded federal action levels. The IEPA report identified only one violation for public notification of lead contamination in the state in 2015.

The report suggests better public awareness, data sharing between the IEPA and the IDPH and mitigation action to eliminate potential lead exposure in the 20 percent of Illinois water systems that have lead service lines.

McSweeney said the results of the report show the need to stay on top of the issue.

"The first step was the governor signing the bill today," he said. "The next step is to continue to ensure there is proper monitoring and look at other legislative solutions as it becomes necessary."