Monticello, IL
Lead reported as not detected
Latest 90th-percentile lead: reported as 0 (not detected) (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. The latest 90th-percentile result was reported as 0 (not detected at the lab's limit). That says the sampled homes were low, not that your home has no lead service line. Check your utility's service line inventory for your address.
Monticello at a glance
Monticello serves about 5,548 people through 2,860 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 groundwater, in Piatt County, Illinois. EPA system ID: IL1470350; phone on file: 217-762-2583. Ask them for your address in their service line inventory - every system had to publish one by Oct 2024.
Monticello's lead record
Against the period ending 2025 (1 ppb) the latest result is about the same. The highest 90th-percentile result EPA holds for Monticello is 5 ppb across 17 monitoring periods, none of them over 15 ppb.
| Period ending | 90th-percentile lead |
|---|---|
| 2025 | 0 (not detected) |
| 2025 | 1 ppb |
| 2025 | 0 (not detected) |
| 2024 | 0 (not detected) |
| 2023 | 0 (not detected) |
| 2022 | 1.4 ppb |
| 2021 | 1.4 ppb |
| 2021 | 1.4 ppb |
| 2020 | 2.5 ppb |
| 2020 | 1.9 ppb |
| 2019 | 1.5 ppb |
| 2019 | 1.4 ppb |
| 2018 | 2.3 ppb |
| 2018 | 1.9 ppb |
| 2017 | 3.6 ppb |
| 2017 | 5 ppb |
| 2016 | 2 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. Monticello's reported as 0 (not detected) sits at the 48th percentile in Illinois and the 35th nationally (higher means more lead). Systems reporting 0 tie at the bottom, so the rank mostly reflects size among them.
Neighbouring systems
8 other systems share Piatt County; 3 of them have a higher latest lead result than Monticello. If you are unsure which one supplies your house, the name on your water bill decides it.
| System | People | Latest lead |
|---|---|---|
| Bement | 1,661 | 0.7 ppb |
| Cerro Gordo | 1,350 | 8.53 ppb |
| Mansfield | 939 | 0.7 ppb |
| White Heath Waterworks | 685 | 0 (not detected) |
| Hammond | 478 | 0 (not detected) |
| De Land | 446 | 0 (not detected) |
| Cisco | 242 | 0 (not detected) |
| Piatt County Nursing Home | 93 | - |
What to do in your house
Look up your address in Monticello's service line inventory. If it says lead, galvanized or unknown, test your tap. If your own line is lead, replacing the private side runs about $1,200-$12,300 (EPA average about $4,700). Ask Monticello whether it covers that cost before hiring anyone - many utilities now do. Its latest copper 90th percentile is 1400 ppb (copper action level 1,300 ppb).
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. Small systems behave differently: why small systems go over more often.