Iron, lead, manganese, arsenic, and chloride are present in Cook County groundwater and well owners should be aware of them. Several of these contaminants exceed EPA health standards, making testing important.
The bedrock beneath Cook County contains iron-bearing minerals and naturally occurring arsenic that dissolve into groundwater as water moves slowly through cracks and spaces in the rock. Chloride enters from road salt and other surface sources. Lead also comes from the bedrock itself.
Groundwater in this county is soft, with moderate iron being the main mineral character. Iron concentrates in the water because it is naturally abundant in the local rock formation. Elevated iron is common across wells in this county, though levels vary from well to well.
Wells in Cook County commonly exceed EPA health standards for arsenic, lead, chloride, iron, and manganese. Arsenic and lead are toxic metals that build up in your body over time and damage your organs and nervous system. Manganese at high levels can harm your brain and affect how your body processes other minerals. Chloride at elevated levels can affect people on low-sodium diets. Iron, while not directly toxic at these levels, can still harm your blood and organs with long-term exposure.
The water in this county is relatively soft, which is good news for scale buildup on pipes and appliances. However, you may notice rust-colored or orange stains on sinks, toilets, and laundry from the iron. Some people also notice a metallic taste in the water. These stains are stubborn and hard to clean.
We recommend a comprehensive metals and minerals panel test to find out exactly what is in your well, since every well is different and your water may have higher or lower levels than what is common in the county. Testing is the only way to know what is actually there so it can be properly treated. A comprehensive panel typically costs between $200 and $400. Iron and manganese can be addressed with filtration systems and water softeners.
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 ⓘ |
|---|---|---|---|---|---|
| Iron | 92 | 38% | Moderate | High | |
| Lead | 27 | 31% | Moderate | High | |
| Manganese | 77 | 30% | Moderate | High | |
| Arsenic | 25 | 8% | Moderate | Moderate | |
| Chloride | 73 | 3% | Moderate | Low | |
| HFPO-DA (GenX) | 191 | 0% | High | Safe | |
| PFOS | 173 | 0% | High | Low | |
| PFNA | 301 | 0% | High | Low | |
| Nitrite | 11 | 0% | Low | Low | |
| Nitrate | 65 | 0% | Moderate | Low | |
| PFOA | 317 | 0% | High | Low | |
| Fluoride | 29 | 0% | Moderate | Low | |
| Sulfate | 61 | 0% | Moderate | Low | |
| E. coli | 1 | 0% | Low | Safe ⓘ | |
| Fecal Coliform | 1 | 0% | Low | Safe ⓘ | |
| Total Coliform | 1 | 0% | Low | Safe ⓘ | |
| Hardness | 37 | — | — | Moderate | Low |
| pH | 44 | — | — | Moderate | Low |
| Sodium | 53 | — | — | 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.
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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