Manganese and black staining: the well problem everybody blames on iron
Somebody calls and says they've got iron in their well. Nine times out of ten they're partly right and partly wrong, and the part they've got wrong is the part that matters. If the stains are orange and rusty, that's iron. If you're seeing black specks in the toilet tank, a dark ring in the bowl, black flecks in the ice, or gray-black streaks in the laundry, that's manganese, and it is a different metal with a different limit and a different health story. Austin and I end up having this conversation on the tailgate about once a week.
How this was built: All figures come from Jones Air & Water's own 57-town water dataset, built from utility consumer confidence reports, USGS and DNR well data, and our own in-home testing, pulled in 2026. Where a number is a measured figure I've said so, and where our notes describe a typical regional range rather than a measurement, I've said that too.
The one number that explains why manganese gets missed
Iron and manganese have different staining thresholds, and they are not close. Our records state both limits plainly: the secondary standard for iron is 300 ppb, and for manganese it is 50 ppb.
That's the whole thing in a sentence. Manganese will wreck your fixtures at one sixth the concentration iron needs. So you can have a well with an iron number that looks almost respectable and a manganese number quietly six or ten times over its own limit, and the homeowner still says "I've got iron," because iron is the word everybody knows.
What our records actually measured in the American Bottoms
The river-bottom alluvial aquifer on the Illinois side is the worst of it in our territory. Our notes for Alton, Bethalto, Granite City, Godfrey and Wood River all describe the same aquifer, and the USGS numbers in our file are blunt.
| What our file records | Measured | Secondary limit | Multiple of limit |
|---|---|---|---|
| Iron, American Bottoms wells | up to 82,000 ppb | 300 ppb | about 273x |
| Manganese, American Bottoms wells | up to 5,300 ppb | 50 ppb | 106x |
People look at 82,000 against 5,300 and conclude the iron is the whole problem. Look at the last column instead. Both of those are catastrophic relative to their own thresholds, and the manganese at 106 times its limit is not a rounding error next to the iron. It is a full second problem that needs its own answer.
Bethalto, where this stopped being theoretical
The clearest case in our whole dataset is a city tap, not a well. Our Bethalto record lists manganese as the brown-water culprit, with 54.9 ppb average at the tap, roughly 500 ppb in the raw well water, and resident samples running as high as 7,480 ppb. The average at the tap is already over the 50 ppb line. The high resident sample is about 150 times it.
Our notes pair that with aging cast-iron water mains causing intermittent brown and discolored water, and they record what happened next: the city's position was that the water meets all standards, while more than a thousand residents filled a Facebook group with brown water photos in 2025 and the school district switched to bottled water.
I'm not writing that to pick a fight with Bethalto. I'm writing it because it is the cleanest illustration I have of the point. The water was compliant. The manganese was real. Both of those things were true at the same time, and a homeowner with a filter did not have to wait for anybody's flushing schedule.
How widespread it is out here
Manganese turns up in the well notes for nearly every town in our dataset. A few worth naming because our records are specific about it:
In Augusta, our notes say iron exceeds the standard in nearly all monitored river-bottom wells and manganese exceeds it widely, with black staining and an infant neurological concern. In St. Charles, our file says iron, manganese and sulfate routinely exceed the secondary limit according to USGS, and calls out black manganese staining specifically. In Godfrey, the record puts iron up to 82 mg/L against a 0.3 limit and manganese up to 5.3 mg/L, and ties the manganese directly to black stains plus a neurological health concern for infants.
That last part is the one people don't expect, so it's worth saying plainly.
Manganese is the one with the health note attached
Iron at these levels is a nuisance contaminant. It stains, it tastes metallic, it clogs aerators, it ruins laundry. What it is not, in our records, is a flagged health risk.
Manganese is different. Our Augusta notes flag an infant neurological concern. Our Godfrey record describes a neurological health concern for infants, and our Godfrey health notes go further, naming manganese and nitrate as the two that specifically threaten infants and babies on formula. If you are mixing formula with untreated well water in the river bottoms, manganese is a reason to get a number rather than a guess.
Three things people mistake for manganese, and one for sulfur
Black slime is usually not manganese staining. Our O'Fallon notes describe hydrogen sulfide with black slime and sulfur bacteria, and our Gerald notes mention slimy iron bacteria. Slime is biological. Manganese staining is gritty and mineral, it wipes into a smear rather than a film, and it comes back on a schedule tied to use rather than to standing water.
A rotten egg smell is hydrogen sulfide, which shows up in the deeper reducing wells all over our notes, and it is a separate fix again. Orange and rust is iron. Gray to black on porcelain, in the laundry, and around the toilet waterline is manganese. If you have all four at once, which is common in a river-bottom well, you have a treatment train and not a single cartridge, and anybody who tells you one filter solves all of it has not looked at your water.
What we actually install for it
The honest answer is that it depends on the number, which is why we test before we quote. Our own notes on Edwardsville say the iron level there needs an iron and oxidation filter, and for the deep bedrock wells our St. Clair notes say to lead with a softener plus filtration and test for radium separately. That's the usual shape of it: oxidation and backwashing filtration to take the metals out, and a softener sized to your actual grains for the hardness that is almost always riding along with it, since our well notes across the region put private wells at 15 to 25 plus grains.
What I would not do is buy equipment off a symptom. Black specks could be manganese, could be sulfur bacteria, could be a failing rubber flapper in the toilet tank shedding into the bowl. The test costs you nothing and it decides which of those you are actually fighting.
For where your town lands on hardness, see the hardest water towns we serve, ranked by the numbers, and for the broader picture of what 30 years of testing wells around here has taught me, see well water vs. city water.
Frequently Asked Questions
How do I tell manganese from iron without a test?
Is manganese in well water actually dangerous?
Will a water softener remove manganese?
Schedule a Free Water Test With Jones Air & Water
If you've got black staining and you've been treating it as an iron problem, there's a decent chance you've been buying the wrong equipment. I'll test your water at your sink, give you the iron and the manganese as two separate numbers, and tell you honestly which one is driving what you're seeing.
Schedule your free water test or see the filtration systems we install for iron and manganese.