Oak Lawn, IL
Lead detected, under the action levels
Latest 90th-percentile lead: 9.3 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. 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
Oak Lawn serves about 58,362 people through 16,766 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 Cook County, Illinois. EPA system ID: IL0312220; phone on file: 708-499-7749. Call that number and ask whether your address has a lead, galvanized or unknown service line.
Oak Lawn's lead record
That is up 8.29 ppb from 1.01 ppb in the period ending 2025. The highest 90th-percentile result EPA holds for Oak Lawn is 11.3 ppb across 10 monitoring periods, none of them over 15 ppb (2 over 10 ppb).
| Period ending | 90th-percentile lead |
|---|---|
| 2026 | 9.3 ppb |
| 2025 | 1.01 ppb |
| 2025 | 0.33 ppb |
| 2025 | 11.3 ppb over 10 |
| 2025 | 10.6 ppb over 10 |
| 2024 | 5.93 ppb |
| 2023 | 6.86 ppb |
| 2022 | 4.36 ppb |
| 2020 | 2.83 ppb |
| 2017 | 5.08 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. Oak Lawn's 9.3 ppb sits at the 95th percentile in Illinois and the 97th nationally (higher means more lead).
Nearby utilities
154 other systems share Cook County; 15 of them have a higher latest lead result than Oak Lawn. 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 |
| Orland Park | 58,020 | 0 (not detected) |
| Berwyn | 57,250 | 2.35 ppb |
Your move
Test your own tap with a certified lab first-draw sample; Oak Lawn, 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 Oak Lawn 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. What a 90th-percentile result does and does not tell you: how to read a lead result. The action level is dropping - the 10 ppb rule from 2027.