Lead Service Lines in Illinois

Your water system's inventory is the record that answers that for your address: it is the utility's account of what it believes each line is made of, and in Illinois 530,643 lines, 14 percent of everything reported, are recorded as lead status unknown. No public dataset answers it for a single address, and EPA's own rule language for the unknown category is "Identify the material of all unknown service lines by the replacement deadline." The sequence is: find the systems serving your area with the ZIP tool on this page, read that system's inventory for your address, and if it says unknown, ask the utility what it plans to do about it. A laboratory test of your own tap is the only thing that measures your water.

As of the April to June 2026 federal extract, Illinois's 1,787 community water systems reported 615,181 lead service lines, 57,081 galvanized lines requiring replacement, 530,643 of unknown material and 2,581,466 non lead. 148 of those systems reported no service line types at all, which is not the same as reporting none: a blank is a blank. 1,155 systems report that every line they own has been identified.

It is EPA's fourth category and the one people find most surprising, because the pipe itself is not lead. In EPA's words: "A GRR service line is a galvanized service line that currently is or ever was downstream of an LSL or is currently downstream of a service line of unknown material." Galvanized iron and steel corrode into a rough interior that can trap lead particles washed down from a lead line upstream, and it keeps releasing them after that lead line is gone. That is why the rule treats it the same as lead for replacement. Illinois utilities reported 57,081 of them.

EPA's Lead and Copper Rule Revisions set the first deadline: "All systems must develop an initial lead service line (LSL) inventory by October 16, 2024, that includes all service lines, regardless of ownership, categorized as lead, non-lead, galvanized requiring replacement (GRR), and unknown." The Lead and Copper Rule Improvements then added a second, fuller one: "Develop an updated initial service line inventory, called the LCRI baseline inventory, that includes updated service line information and connectors. The baseline inventory is due by November 1, 2027." On replacement, EPA states: "EPA is requiring water systems to conduct full replacement of all lead and galvanized requiring replacement (GRR) service lines that are under the control of the water system in 10 years or less, with limited exceptions, regardless of the water system’s 90th percentile lead level." In Illinois, 144 community systems carry a listed LSL Inventory violation in the federal file, EPA's record that the inventory owed was not produced.

Illinois is one of five states with a verified statewide service line resource that loads and carries service line materials. A statewide spreadsheet, one row per water system, with each system's reported lead, galvanized and unknown service line counts and its county. It is published by the state, linked on this page, and it sits alongside the federal per system counts in the ZIP tool above. For anything it does not answer, Illinois Environmental Protection Agency and your own utility hold the underlying record.

No, and two separate things are worth keeping apart. The number EPA lists per system is a 90th percentile from Lead and Copper Rule tap sampling, computed across a targeted pool of higher risk homes, not a measurement of any one house. In Illinois, 1,737 systems have a result from a monitoring period ending in the last five years, and 18 of those sit at or above EPA's 15 parts per billion action level. The action level is not a health threshold: it is the point at which the rule requires a system to act, and EPA writes that "EPA and the Centers for Disease Control and Prevention (CDC) agree that there is no known safe level of lead in a child’s blood." 12 Illinois systems have no listed result newer than five years, so for those the federal record is simply old.

Yes, and this is the most common misreading of an inventory. EPA: "Among homes without lead service lines, the most common problem is with brass or chrome-plated brass faucets and plumbing with lead solder." The inventory covers the service line, the pipe between the water main and the building. It does not cover the plumbing inside your walls, the solder in its joints, or the fixtures on the end of it, and lead was legal in all three long after it stopped being used for service lines. That matters in Illinois in proportion to how much of it was built before 1986, and it applies to every one of the 2,581,466 lines Illinois utilities recorded as non lead just as much as to the 530,643 they have not identified. EPA also notes how lead gets in at all: "Lead can enter drinking water when plumbing materials that contain lead corrode, especially where the water has high acidity or low mineral content that corrodes pipes and fixtures. The most common sources of lead in drinking water are lead pipes, faucets, and fixtures."

From two federal records, both current to the April to June 2026 extract. The service line counts come from EPA's SDWIS service line inventory report, one row per water system, carrying EPA's four categories: for Illinois that is 1,787 community water systems and 3,784,371 reported lines. The tap results and the violation counts come from EPA's quarterly Safe Drinking Water Act download, which is where the 144 listed Illinois inventory violations and the 1,737 recent lead results on this page come from. Both are US Government works in the public domain. They cover reported service lines and compliance records; a specific address, anything a Illinois utility did not report, and private wells, which no lead rule covers, are outside both. EPA's own caution on the compliance data applies throughout: "Compliance statistics are based on violations reported by states to the EPA Safe Drinking Water Information System (SDWIS). EPA is aware of inaccuracies and underreporting of some data in this system. We are working with the states to improve the quality of the data."

In the older cities, almost always. 329 Illinois community systems reported at least one lead service line, and those systems together report serving 8.4 million people. EPA's framing of why it matters: "Where lead service lines (LSLs) are present, they represent the greatest lead exposure source in drinking water." The ZIP tool above lists the systems serving your counties and what each one reported, which is a far better guide than any statewide figure.