Water Quality
The 2025 water report card for Marengo and ten neighboring towns, side by side. All eleven systems draw from wells, so the comparison is fair. Pick the towns you want to compare, and tap any town's name to read its full report.
2025 Consumer Confidence Reports · Illinois EPA dataEach town's own published numbers. This is a side-by-side, not a ranking: water quality is not a single score, and a town that tests more can look worse on paper.
▲ over a limit● at the action levelND non-detectn/r not reported in that report
| Town | Leadppb · AL 15 | Copperppm · AL 1.3 | RadiumpCi/L · MCL 5 | Nitrateppm · MCL 10 | TTHMppb · MCL 80 | HAA5ppb · MCL 60 | Manganeseppb · IL MCL 150 |
|---|---|---|---|---|---|---|---|
| Marengo HomeMcHenry Co. | ND | 0.595 | 0.63 | 1 | 25 | 11 | 120–380 |
| Algonquin McHenry Co. | 3.3 | 1.3 | 3 | 1 | 63 | 35 | 36 |
| Belvidere Boone Co. | 1.8 | 0.48 | 0.931 | 2 | 16 | 9 | 2.2 |
| Crystal Lake McHenry Co. | 9.3 | 1.0 | 3 | n/r | 60 | 10 | 2.1 |
| Genoa DeKalb Co. | 10 | 0.846 | 5.92–8.49† | 0.03 | 19 | 4 | 26 |
| Hampshire Kane Co. | 2.14 | 0.608 | 3 | 0.113 | 11 | 3 | n/r |
| Harvard McHenry Co. | 1.4 | 0.38 | 3.29 | 1 | 5 | 4 | 7.8 |
| Hebron McHenry Co. | 4.5 | 0.39 | 1.01 | 2 | 16 | 1 | 80 |
| Huntley McHenry Co. | 3 | 1.1 | 4 | n/r | 13 | 6 | n/r |
| Lake in the Hills McHenry Co. | 2.7 | 1.4 | 2 | n/r | 40 | 18 | 19 |
| Woodstock McHenry Co. | 7 | 1.2 | 1.28 | 2 | 58 | 30 | 25 |
† Genoa's radium figure. Genoa's state-generated 2025 report prints a "highest level detected" of 4 pCi/L for combined radium alongside a range of 5.92–8.49. The "4" is a regulatory compliance average that still reflected pre-2025 below-limit results, not a 2025 measurement; per IEPA Drinking Water Watch sample records (PWS IL0370150), the four 2025 samples at the Well 4 entry point were 5.92 (Apr 16), 8.49 (Aug 1), 7.11 (Sep 4) and 8.20 (Oct 2) pCi/L. Radium compliance is determined by a running annual average, and IEPA issued an MCL violation for Well 4 on May 15, 2026, with public notice completed June 15, 2026. Source: IEPA Drinking Water Watch sample results and violation detail, accessed July 12, 2026.Genoa's state-generated report prints a lower radium figure (4 pCi/L) than its four 2025 samples. See the full comparison for why.
Five of the eleven reports list at least one violation for 2025. Report cards like these almost always have something on them; here is what each one listed.
Nothing listed for 2025: Algonquin, Belvidere, Crystal Lake, Hampshire, Harvard, Hebron. We count only what each report card itself lists; state and federal compliance databases show additional administrative items for some towns.
How to read this. Every figure comes from the town's 2025 Consumer Confidence Report, the standardized annual report card Illinois requires of municipal water systems, as published through the Illinois EPA's Drinking Water Watch. Lead and copper are 90th-percentile results judged against an action level (AL); the other columns are the highest level detected, judged against a maximum contaminant level (MCL). Manganese is regulated by Illinois as an aesthetic standard. All eleven systems pump groundwater.
Not a ranking. Different wells carry different minerals, samples are taken at different times, and a town that tests more can look worse on paper while being no different at the tap. Detection is not danger; every figure here except the flagged ones is under its limit.
Sources. Tap any town's name to open its report (PDF, as downloaded July 2026). Marengo's is the city's own 2025 report; the others are the state-generated reports for each system. Figures verified against Drinking Water Watch, July 2026.