Lake Zurich, IL
Lead detected, under the action levels
Latest 90th-percentile lead: 4.67 ppb (monitoring period 2025-2025). The federal action level is 15 ppb today and drops to 10 ppb in Nov 2027; EPA's health goal is 0. Lead was measured in sampled homes but the 90th percentile is under both action levels. EPA's health goal for lead is zero, so test your own tap if your home was built before 1986 or anyone in it is pregnant or a young child.
Who runs the water here
Lake Zurich serves about 19,759 people through 6,862 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 groundwater, in Lake County, Illinois. EPA system ID: IL0970850; phone on file: 847-540-1696. Call that number and ask whether your address has a lead, galvanized or unknown service line.
Lead results over time
That is up 1.93 ppb from 2.74 ppb in the period ending 2025. The highest 90th-percentile result EPA holds for Lake Zurich is 10.5 ppb across 10 monitoring periods, none of them over 15 ppb (1 over 10 ppb).
| Period ending | 90th-percentile lead |
|---|---|
| 2025 | 4.67 ppb |
| 2025 | 2.74 ppb |
| 2025 | 6.88 ppb |
| 2025 | 10.5 ppb over 10 |
| 2022 | 3 ppb |
| 2019 | 3.94 ppb |
| 2018 | 9.16 ppb |
| 2017 | 6.73 ppb |
| 2017 | 4.75 ppb |
| 2016 | 4.86 ppb |
Where this result ranks
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. Lake Zurich's 4.67 ppb sits at the 87th percentile in Illinois and the 90th nationally (higher means more lead).
Nearby utilities
103 other systems share Lake County; 22 of them have a higher latest lead result than Lake Zurich. 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) |
| Zion | 24,442 | 11.2 ppb |
| Great Lakes Naval Training Station | 23,000 | 0 (not detected) |
| Grayslake | 21,248 | 11 ppb |
| Libertyville | 20,500 | 5.61 ppb |
Next steps for Lake Zurich, IL
Test your own tap with a certified lab first-draw sample; Lake Zurich, 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 Lake Zurich 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. Size matters more than most people expect: small vs large water systems.