Crystal Lake, IL
Lead detected, under the action levels
Latest 90th-percentile lead: 6.8 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.
Crystal Lake at a glance
Crystal Lake serves about 40,661 people through 14,101 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: IL1110150; phone on file: 815-356-3613. Call that number and ask whether your address has a lead, galvanized or unknown service line.
Crystal Lake's lead record
Against the period ending 2025 (7.7 ppb) the latest result is about the same. The highest 90th-percentile result EPA holds for Crystal Lake is 12 ppb across 13 monitoring periods, none of them over 15 ppb (1 over 10 ppb).
| Period ending | 90th-percentile lead |
|---|---|
| 2026 | 6.8 ppb |
| 2025 | 7.7 ppb |
| 2025 | 1.3 ppb |
| 2025 | 4.3 ppb |
| 2025 | 9.3 ppb |
| 2024 | 12 ppb over 10 |
| 2024 | 4.7 ppb |
| 2023 | 7.4 ppb |
| 2023 | 5.6 ppb |
| 2022 | 5.3 ppb |
| 2022 | 5.1 ppb |
| 2020 | 3.77 ppb |
| 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. Crystal Lake's 6.8 ppb sits at the 92nd percentile in Illinois and the 94th nationally (higher means more lead).
Neighbouring systems
31 other systems share Mchenry County; 2 of them have a higher latest lead result than Crystal Lake. If you are unsure which one supplies your house, the name on your water bill decides it.
| System | People | Latest lead |
|---|---|---|
| Algonquin | 30,700 | 1.96 ppb |
| Lake In The Hills | 28,661 | 0 (not detected) |
| 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 |
What to do in your house
Test your own tap with a certified lab first-draw sample; Crystal Lake, 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 Crystal Lake 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. Size matters more than most people expect: small vs large water systems.