Zion, IL
Above the new 10 ppb level coming in 2027
Latest 90th-percentile lead: 11.2 ppb (monitoring period 2026-2026). The federal action level is 15 ppb today and drops to 10 ppb in Nov 2027; EPA's health goal is 0. Under the current 15 ppb rule this is not an exceedance, but it is above the 10 ppb action level that takes over in Nov 2027. Test your own tap; filter if your result shows lead.
About Zion
Zion serves about 24,442 people through 7,080 service connections, which makes it a large system under EPA's size classes. It is owned by a local government (city, town, county or district) and draws surface water, in Lake County, Illinois. EPA system ID: IL0972000; phone on file: 847-746-4054. Call that number and ask whether your address has a lead, galvanized or unknown service line.
Every lead result on file
That is up 11.2 ppb from 0 ppb in the period ending 2025. The highest 90th-percentile result EPA holds for Zion is 13.1 ppb across 8 monitoring periods, none of them over 15 ppb (3 over 10 ppb).
| Period ending | 90th-percentile lead |
|---|---|
| 2026 | 11.2 ppb over 10 |
| 2025 | 0 (not detected) |
| 2025 | 0 (not detected) |
| 2025 | 10.5 ppb over 10 |
| 2025 | 13.1 ppb over 10 |
| 2023 | 0 (not detected) |
| 2020 | 0 (not detected) |
| 2017 | 0 (not detected) |
How Zion compares
Of the 1,744 Illinois systems with a lead result, the median latest reading is 0 ppb; 22 are over 15 ppb right now and 152 have gone over at some point. Zion's 11.2 ppb sits at the 97th percentile in Illinois and the 98th nationally (higher means more lead).
Other water systems in Lake County
103 other systems share Lake County; 6 of them have a higher latest lead result than Zion. If you are unsure which one supplies your house, the name on your water bill decides it.
| System | People | Latest lead |
|---|---|---|
| Waukegan | 87,149 | 10 ppb |
| Vernon Hills - Lake Co Pw | 33,207 | 0 (not detected) |
| Mundelein | 31,500 | 4.3 ppb |
| Gurnee | 30,193 | 0.3 ppb |
| Highland Park | 30,176 | 0 (not detected) |
| Round Lake Beach | 27,200 | 0 (not detected) |
| Great Lakes Naval Training Station | 23,000 | 0 (not detected) |
| Grayslake | 21,248 | 11 ppb |
| Libertyville | 20,500 | 5.61 ppb |
| Lake Zurich | 19,759 | 4.67 ppb |
What to do in your house
Test your own tap with a certified lab first-draw sample; Zion, IL may offer free or low-cost kits through the utility. If your own line is lead, replacing the private side runs about $1,200-$12,300 (EPA average about $4,700). Ask Zion whether it covers that cost before hiring anyone - many utilities now do.
These figures describe homes the utility sampled, not your tap. Only your service line record or a test of your own water answers the question for your house. Why sampled homes are the worst-case ones is in the guide to reading the number. See what changes at 10 ppb in 2027.