Lake In The Hills, 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.
Who runs the water here
Lake In The Hills serves about 28,661 people through 9,590 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 Mchenry County, Illinois. EPA system ID: IL1110400; phone on file: 847-960-7520. They can tell you what your service line is made of and whether they pay to replace it.
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 Lake In The Hills is 4 ppb across 14 monitoring periods, none of them over 15 ppb.
| Period ending | 90th-percentile lead |
|---|---|
| 2025 | 0 (not detected) |
| 2025 | 0 (not detected) |
| 2025 | 2.7 ppb |
| 2025 | 2 ppb |
| 2024 | 3.1 ppb |
| 2024 | 4 ppb |
| 2023 | 1.7 ppb |
| 2023 | 1.4 ppb |
| 2022 | 1.9 ppb |
| 2022 | 1.3 ppb |
| 2021 | 2.8 ppb |
| 2021 | 2 ppb |
| 2020 | 3.5 ppb |
| 2017 | 0 (not detected) |
How Lake In The Hills 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. Lake In The Hills's reported as 0 (not detected) sits at the 54th percentile in Illinois and the 39th nationally (higher means more lead). Systems reporting 0 tie at the bottom, so the rank mostly reflects size among them.
Neighbouring systems
31 other systems share Mchenry County; 20 of them have a higher latest lead result than Lake In The Hills. If you are unsure which one supplies your house, the name on your water bill decides it.
| System | People | Latest lead |
|---|---|---|
| Crystal Lake | 40,661 | 6.8 ppb |
| Algonquin | 30,700 | 1.96 ppb |
| Huntley | 28,495 | 1.1 ppb |
| Woodstock | 25,630 | 1.5 ppb |
| Mchenry | 22,335 | 6.7 ppb |
| Cary | 17,826 | 1.7 ppb |
| Harvard | 9,469 | 7.1 ppb |
| Il American-Whispering Hills | 8,300 | 0 (not detected) |
| Marengo | 7,572 | 0 (not detected) |
| Fox River Grove | 4,702 | 6.4 ppb |
Next steps for Lake In The Hills, IL
Look up your address in Lake In The Hills'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 Lake In The Hills 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.