Groundwater in Nassau County contains iron, chloride, sulfate, and fluorinated chemicals known as PFOA, PFOS, and PFNA. Several of these contaminants exceed EPA health standards and warrant attention from well owners.
Iron dissolves naturally from the sand and gravel layers that make up the aquifer beneath Nassau County. Chloride and sulfate enter groundwater from road salt spread during winters, from septic systems, and from saltwater intrusion near coastal areas. The fluorinated chemicals come from industrial and commercial sources, including firefighting foam and certain manufacturing processes that have contaminated groundwater over time.
Groundwater in Nassau County is notable for its high iron content, which concentrates in the water as it moves through iron-rich sediments in the aquifer. Many wells across the county show elevated iron levels along with moderate sodium and low sulfate. These mineral and chemical signatures are widespread, appearing in wells throughout the region.
Wells in Nassau County commonly exceed EPA health standards for chloride, iron, and PFAS chemicals including PFNA, PFOA, and PFOS. Exposure to PFAS compounds has been linked to effects on the immune system, thyroid function, and liver health, particularly with long-term drinking water exposure. Elevated chloride can affect people with heart disease or high blood pressure. Iron itself does not pose a direct health risk at the levels found in county wells, but it is included here because of its presence alongside other contaminants.
Iron in county well water leaves orange or brown stains on laundry, sinks, and fixtures that are difficult to remove. You may notice a metallic or bitter taste in your water. The combination of minerals in this area creates moderate hardness, which can shorten the lifespan of water heaters and dishwashers over time by leaving scale buildup inside the equipment.
We recommend testing your well water to find out what is actually in it, since every well is different and yours may have higher or lower levels than what is common in the county. A comprehensive metals and minerals panel that checks for all these contaminants typically costs $200 to $400. Treatment options like reverse osmosis filters or ion exchange softening can address multiple contaminants once you know your results.
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 | 15506 | 33% | High | High | |
| Manganese | 15230 | 19% | High | High | |
| PFOA ⓘ municipal | 374 | 7% | High | Moderate | |
| Nitrate | 15474 | 5% | High | Moderate | |
| PFOS ⓘ municipal | 374 | 2% | High | Low | |
| Chloride | 17777 | 2% | High | Low | |
| Lead | 3469 | 2% | High | Low | |
| PFNA ⓘ municipal | 374 | 1% | High | Low | |
| Sulfate | 11115 | 1% | High | Low | |
| Arsenic | 2308 | 0% | High | Low | |
| Nitrite | 15138 | 0% | High | Low | |
| Fluoride | 6825 | 0% | High | Low | |
| HFPO-DA (GenX) ⓘ municipal | 374 | 0% | High | Safe | |
| PFHxS ⓘ municipal | 374 | 0% | High | Low | |
| Radon | 9 | 0% | Low | Low ⓘ | |
| Uranium | 22 | 0% | Moderate | Low | |
| PFBS ⓘ municipal | 374 | — | High | Low | |
| Hardness | 15318 | — | High | Low | |
| Fecal Coliform | 3* | 0% | Low | Low ⓘ | |
| E. coli | 4* | 0% | Low | Safe ⓘ | |
| pH | 16882 | — | High | Low | |
| Sodium | 10355 | — | High | Low | |
| Total Coliform | 4* | 0% | Low | 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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