Rosemont, IL
Exceeded the action level in the past
Latest 90th-percentile lead: reported as 0 (not detected) (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. The latest result is under the action level, but this system has gone over 15 ppb before. Lead comes from pipes, not the source water, so a home with a lead service line can still be exposed. Test your own tap.
Who runs the water here
Rosemont serves about 3,952 people through 721 service connections, which makes it a medium-sized system under EPA's size classes. It is owned by a local government (city, town, county or district) and draws surface water, in Cook County, Illinois. EPA system ID: IL0312760; phone on file: 847-698-3744. Call that number and ask whether your address has a lead, galvanized or unknown service line.
Lead results over time
Against the period ending 2025 (0 ppb) the latest result is about the same. The highest 90th-percentile result EPA holds for Rosemont is 27 ppb across 8 monitoring periods, 1 of them over the 15 ppb action level.
| Period ending | 90th-percentile lead |
|---|---|
| 2026 | 0 (not detected) |
| 2025 | 0 (not detected) |
| 2025 | 1.5 ppb |
| 2025 | 0 (not detected) |
| 2025 | 27 ppb over 15 |
| 2023 | 1.3 ppb |
| 2020 | 0 (not detected) |
| 2017 | 0 (not detected) |
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. Rosemont's reported as 0 (not detected) sits at the 46th percentile in Illinois and the 34th nationally (higher means more lead). Systems reporting 0 tie at the bottom, so the rank mostly reflects size among them.
Other water systems in Cook County
154 other systems share Cook County; 99 of them have a higher latest lead result than Rosemont. If you are unsure which one supplies your house, the name on your water bill decides it.
| System | People | Latest lead |
|---|---|---|
| Chicago | 2,721,308 | 6.4 ppb |
| Cicero | 83,000 | 5 ppb |
| Schaumburg | 75,750 | 0.87 ppb |
| Evanston | 74,486 | 6.5 ppb |
| Arlington Heights | 73,320 | 7.6 ppb |
| Palatine | 70,875 | 8.9 ppb |
| Skokie | 66,422 | 9.77 ppb |
| Des Plaines | 60,675 | 5.7 ppb |
| Oak Lawn | 58,362 | 9.3 ppb |
| Orland Park | 58,020 | 0 (not detected) |
Next steps for Rosemont, IL
Test your own tap with a certified lab first-draw sample; Rosemont, 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 Rosemont 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. The lead result guide covers how utilities pick the homes they sample. Why an old exceedance still matters: over the limit before, under it now.