Groundwater in St. Louis County contains arsenic, chloride, fluoride, iron, lead, manganese, radon, and PFOA and PFOS chemicals. Multiple contaminants exceed EPA health standards, making testing and treatment important for your well.
The rock layers beneath this county naturally hold these contaminants. Arsenic, iron, and manganese dissolve from the rock as water moves slowly underground. Lead can come from old pipes or service lines. Radon seeps up from the rock itself. PFOA and PFOS are industrial chemicals that have entered groundwater from surface sources and now persist in the water supply.
Groundwater in this county is hard, driven by elevated calcium and magnesium from the rock below. As water passes through the ground layers, it picks up these minerals and holds onto them. Hard water is widespread across wells throughout the county.
Wells in St. Louis County contain multiple contaminants that exceed EPA health standards. Arsenic, lead, and radon are toxic substances that build up in your body over time and increase cancer risk. Fluoride at elevated levels can damage tooth enamel in children. PFOA, PFOS, and PFHXS are chemicals that persist in your body and blood. Chloride and sulfate at high levels affect people with heart disease or high blood pressure. Manganese exposure can harm the nervous system.
County wells are moderately hard, which leaves scale buildup on fixtures and inside pipes. You may notice a metallic taste from iron and spots on dishes after washing. Hard water can shorten the lifespan of water heaters and dishwashers. The water is low in sodium, which is good for your health.
Testing your specific well is essential because every well is different and your water may have higher or lower levels than what is common in the county. We recommend a comprehensive metals and minerals panel, which typically costs $200-400. Testing is the only way to know what is actually in your water so you can treat it properly. Water softeners, reverse osmosis systems, and specialized filters remove these contaminants.
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 ⓘ |
|---|---|---|---|---|---|
| Radon | 1 | 100% | Low | High ⓘ | |
| Manganese | 504 | 57% | High | High | |
| PFOA ⓘ municipal | 169 | 48% | High | High | |
| PFOS ⓘ municipal | 150 | 43% | High | High | |
| Iron | 519 | 31% | High | High | |
| PFHxS ⓘ municipal | 80 | 26% | Moderate | High | |
| Chloride | 588 | 6% | High | Moderate | |
| Arsenic | 419 | 5% | High | Moderate | |
| Lead | 440 | 3% | High |
Moderate
Elevated concentration, not % above limit
|
|
| Sulfate | 523 | 1% | High | Low | |
| Fluoride | 445 | 0% | High | Low | |
| Uranium | 1 | 0% | Low | Low ⓘ | |
| Nitrate | 83 | 0% | Moderate | Low | |
| Nitrite | 23 | 0% | Moderate | Low | |
| HFPO-DA (GenX) ⓘ municipal | 54 | 0% | Moderate | Safe | |
| PFNA ⓘ municipal | 80 | 0% | Moderate | Low | |
| Hardness | 192 | — | High | Low | |
| PFBS ⓘ municipal | 62 | — | Moderate | Low | |
| pH | 158 | — | High | Low | |
| Sodium | 544 | — | High | 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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