La Salle County groundwater contains radon, sulfate, and chloride as the top detected contaminants, with arsenic, chloride, fluoride, iron, manganese, radon, and sulfate exceeding EPA health standards at concerning levels.
The rocks beneath La Salle County naturally contain radioactive minerals that release radon into groundwater as water moves slowly through the formation. Saltwater and minerals from ancient marine deposits accumulate in the pores of the rock, concentrating chloride and sulfate over time. Oil and gas activity in the region can also mobilize deep minerals and contaminants toward drinking water zones.
Groundwater in this county is not hard but is notably high in sodium, driven by the county's coastal uplands geology where seawater influence and mineral-rich rock layers concentrate sodium in the water. The moderate levels of iron and sulfate also shape the water's character in many wells. These mineral and contaminant patterns are widespread across wells throughout La Salle County.
Wells in La Salle County contain arsenic, fluoride, and radon at levels that exceed EPA health standards. Arsenic can damage your organs and increase cancer risk over time. Fluoride at these levels can cause dental problems and bone damage. Radon is a radioactive gas that enters your lungs and increases the risk of lung cancer.
The county's groundwater also has very high sodium content and elevated sulfate and iron. You may notice a salty or bitter taste in your water. Iron can stain your laundry, dishes, and bathroom fixtures with rust-colored marks. Sulfate can create an unpleasant odor.
Because multiple contaminants exceed EPA standards in this county, we recommend a comprehensive metals and minerals panel to find out what is actually in your well. Your well could have higher or lower levels than what is common here. Testing is the only way to know what treatment your water needs. A comprehensive panel typically costs $200 to $400. Reverse osmosis systems or activated carbon filters can treat many of these concerns.
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 | 2 | 50% | Low | High ⓘ | |
| Sulfate | 124 | 35% | High | High | |
| Chloride | 126 | 28% | High | High | |
| Iron | 210 | 24% | High | High | |
| Manganese | 125 | 7% | High | Moderate | |
| Arsenic | 108 | 2% | High | Low | |
| Fluoride | 340 | 2% | High | Low | |
| HFPO-DA (GenX) ⓘ municipal | 7 | 0% | Low | Safe ⓘ | |
| Lead | 110 | 0% | High | Low | |
| Nitrate | 140 | 0% | High | Low | |
| Nitrite | 6 | 0% | Low | Safe ⓘ | |
| PFHxS ⓘ municipal | 7 | 0% | Low | Safe ⓘ | |
| PFNA ⓘ municipal | 7 | 0% | Low | Safe ⓘ | |
| PFOA ⓘ municipal | 7 | 0% | Low | Safe ⓘ | |
| PFOS ⓘ municipal | 7 | 0% | Low | Safe ⓘ | |
| Uranium | 28 | 0% | Moderate | Low | |
| Sodium | 124 | — | High | Low | |
| pH | 116 | — | High | Low | |
| PFBS ⓘ municipal | 7 | — | Low | Safe ⓘ | |
| Hardness | 116 | — | 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.
Loading recent water news…