Fillmore County's groundwater contains arsenic, iron, lead, manganese, nitrate, and the industrial chemicals PFOA and PFOS. Multiple contaminants exceed EPA health standards in wells across the county.
The limestone bedrock underneath this county naturally releases arsenic, iron, and manganese as groundwater moves through it over time. Nitrate comes from farm fertilizers and animal waste that seep down into the groundwater. PFOA and PFOS are human-made chemicals that contaminate water through industrial discharge and land disposal.
Groundwater in this county is very hard, driven by calcium and magnesium dissolved from the limestone rock below. The carbonate layers naturally release these minerals as water passes through. Hard water is widespread across Fillmore County wells.
Wells in Fillmore County exceed EPA health standards for arsenic, iron, lead, manganese, nitrate, PFOA, and PFOS. Arsenic damages the kidneys and increases cancer risk. Lead harms brain development in children and raises blood pressure in adults. Manganese affects the nervous system at high levels. Nitrate is especially dangerous for infants and can interfere with oxygen in the blood. PFOA and PFOS are human-made chemicals that build up in your body and weaken the immune system.
The very hard water in this county leaves stubborn white scale on fixtures, pipes, and appliances. You may notice orange or brown staining from iron, a metallic taste, or rotten-egg odor from sulfur. Hard water reduces soap effectiveness and makes cleaning harder. Over time, mineral buildup shortens the lifespan of water heaters, dishwashers, and other appliances.
Testing is the only way to know what is actually in your well so you can treat it properly. Every well is different, and your well may have higher or lower levels than what is common here. We recommend a comprehensive metals and minerals panel, which typically costs between $200 and $400. Water softeners, iron filters, and nitrate treatment systems can address these concerns once you know your specific levels.
Not sure if your well is affected? Get certified results in 5–7 days.
Test Your Well Water with Tap Score →| Contaminant | Samples ⓘ | % Above MCL ⓘ | Distribution ⓘ | Confidence ⓘ | Risk ⓘ |
|---|---|---|---|---|---|
| PFOA ⓘ municipal | 13 | 46% | Low | High | |
| Iron | 116 | 40% | High | High | |
| PFOS ⓘ municipal | 6 | 33% | Low | High ⓘ | |
| Nitrate | 140 | 7% | High | Moderate | |
| Arsenic | 24 | 4% | Moderate |
Moderate
Elevated concentration, not % above limit
|
|
| Lead | 24 | 4% | Moderate |
Moderate
Elevated concentration, not % above limit
|
|
| Manganese | 106 | 4% | High |
Moderate
Elevated concentration, not % above limit
|
|
| Chloride | 324 | 0% | High | Low | |
| Fluoride | 112 | 0% | High | Low | |
| HFPO-DA (GenX) ⓘ municipal | 4 | 0% | Low | Safe ⓘ | |
| Nitrite | 119 | 0% | High | Low | |
| PFHxS ⓘ municipal | 6 | 0% | Low | Low ⓘ | |
| PFNA ⓘ municipal | 7 | 0% | Low | Safe ⓘ | |
| Sulfate | 169 | 0% | High | Low | |
| Sodium | 113 | — | High | Low | |
| pH | 22 | — | Moderate | Low | |
| PFBS ⓘ municipal | 4 | — | Low | Safe ⓘ | |
| Hardness | 21 | — | Moderate | Low |
MCL = Maximum Contaminant Level (EPA limit for public water; used as benchmark for private wells). Distribution shows % of sampled wells in each concentration band. Methodology.
* Microbial contaminants (E. coli, coliform) reflect only samples from the last 10 years.
Data shows potential risk — a certified test confirms whether your water is affected.
Order a Tap Score Test →Population-level CDC data. Not individual risk prediction.
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