How Marengo's Water Compares to Its Neighbors

If you spend any time in Marengo's Facebook groups, you have seen the complaints. The water tastes off. It stains the tub and the laundry. Every so often a thread ends with the conclusion that Marengo's water is just bad, maybe unsafe, and certainly worse than whatever the next town over is drinking. Earlier this month we compared what Marengo charges for water against its neighbors. This is the companion question, and the more heated one: what is actually in the water, and is Marengo really worse off than the towns around it?

So we lined up the evidence. Every municipal water system in Illinois has to publish an annual report card, called a Consumer Confidence Report, built on the same standardized, state-mandated tests. We pulled the 2025 report for Marengo and for ten surrounding towns: Woodstock, Crystal Lake, Harvard, Hebron, Huntley, Lake in the Hills, Algonquin, Hampshire, Genoa, and Belvidere. All of them, like Marengo, draw their water from wells rather than a lake or river, so the comparison is fair. Then we read all eleven.

One caveat before the results. Water quality is not a single score the way a water bill is. 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. So this is not a ranking of best to worst water. It is a side-by-side of what each town's own report says, with links so you can read them yourself.

Want to pick your own towns to compare, or see who had a violation in 2025? Open the full comparison.

Start with the thing people actually notice, because the complaints are not imaginary.

The taste and the staining have a name: manganese. It is a naturally occurring mineral that discolors laundry and plumbing fixtures and throws off the flavor of coffee and tea, and in 2025 Marengo had, by a wide margin, the most of it. Marengo logged the only manganese violation in the group, with samples running as high as 380 parts per billion against a state limit of 150. The next-highest town we checked, Hebron, topped out at 80. The rest that report it came in between roughly 2 and 36, and two towns do not report it at all. If you have tasted something metallic or scrubbed a brown ring out of the tub, the numbers back you up.

Manganese is regulated by Illinois as a nuisance mineral rather than a federal health contaminant, but it is not a purely cosmetic story either. As we covered in our walk through Marengo's report, the EPA advises that water over 300 ppb not be used to mix formula for babies under six months old, and Marengo's fourth-quarter samples ran as high as 380.

Manganese in the wells is also not new. Removing it, along with iron and radium, is the stated purpose of the city's new $7.55 million filtration plant, which opened in June. The plant is the city's answer to exactly this problem, and it is a real one. It is also fair to say the answer arrived after the frustration, not before it. The next report card will show whether the numbers actually fall. We will check.

Safety is a separate question, and it gets a different answer.

On the measures that matter most for health, Marengo is at or near the top of the group. Lead came back non-detect, below the level the lab can even measure, the cleanest result of the eleven towns; no town in the group exceeded the federal action level for lead in 2025. Radium, a naturally occurring radioactive element common in deep Illinois wells, was lower in Marengo than in any other town we checked. Copper was among the lowest, and the only town over the copper action level in 2025 was Lake in the Hills. The compounds that form when water is disinfected came in mid-pack for Marengo, comfortably under their limits, with more towns below Marengo's levels than above.

The bigger picture is that Marengo's water is not unusual for this corner of the county, in the reassuring ways and the concerning ones. Nearly every town here pumps from wells in old industrial and agricultural country, and most carry some susceptibility to solvents in their source water. Marengo's report notes a past detection in one well; so do the reports or state assessments for Harvard, Hebron, Crystal Lake, and Genoa, and several of those detections are sharper than Marengo's. The state rates Lake in the Hills and Belvidere as susceptible too, though neither report lists a detection. That is a regional groundwater story rather than a Marengo one, and it deserves its own article.

Marengo's violation was also not the neighborhood's roughest year. Five of the eleven reports list at least one violation for 2025. In July 2025, Huntley had an E. coli result serious enough to trigger a four-day boil order, the kind of acute, health-based problem Marengo's report does not have. Lake in the Hills went over the copper limit and missed a full year of required testing for disinfection byproducts. Woodstock logged several treatment and reporting violations. Genoa missed a round of nitrite monitoring, and its year turned out worse than its report card suggests: all four of its 2025 radium samples came back above the federal limit, and this spring the state formally cited it, according to Illinois EPA records. We are not listing these to pick on anyone. The point is that report cards like these almost always have something on them, and Marengo's something is a mineral that stains tubs, not bacteria in the water.

Put together, the picture is more specific than the argument usually allows. Two claims tend to travel together: the water tastes bad, and the water is not safe. The first is true, measurably, and was worse here than anywhere nearby. The second is a different question, and on the evidence available, it gets a different answer. By the measures municipal water systems are required to report, Marengo's water is as clean as or cleaner than most of the towns around it, and its one real problem is the one the new plant was built to solve.

One more honest caveat. A report card like this measures the contaminants the state requires it to measure, at designated sampling points in the system. It cannot see your individual service line, your water heater, or the pipes in your walls, and water that tests clean at the system level can still pick up problems inside a single home. Both things can be true at once: the system's numbers can be clean, and the glass in your kitchen can still be telling you something. So if your water looks, smells, or tastes wrong, that is worth acting on rather than shrugging off. Report it to city hall so it is on the record, and ask about getting it tested.

Want to check for yourself? Every town's report is public through the Illinois EPA's drinking water portal, and Marengo's full 2025 report is posted on our site and on the city's Water Safety Dashboard. If you missed them, here is what we found on what Marengo charges for water, and a plain-English walk through Marengo's own water report.