Johnston County sits above the Northern Atlantic Coastal Plain aquifer system, where wells contain fluoride, iron, manganese, nitrate, and PFOS and PFOA at levels that exceed EPA health standards. These contaminant levels are serious enough to warrant testing and attention.
The sand and clay layers that make up this aquifer naturally release iron and manganese as water moves through them. Nitrate and sulfate enter from fertilizer and agricultural practices common across the county. PFOS and PFOA are industrial chemicals that have contaminated groundwater through past manufacturing or disposal, likely from specific sites that affected broader areas.
Groundwater in Johnston County is soft but elevated in iron, which comes naturally from the sand and clay sediments below. The water is not hard because calcium and magnesium remain low, but iron concentration is high across many wells in the county.
Wells in Johnston County contain several contaminants that exceed EPA health standards. Fluoride, nitrate, and the PFAS chemicals PFOA, PFOS, and PFHxS can all harm your health at elevated levels. Fluoride affects bone and teeth development. Nitrate is especially dangerous for infants and can reduce oxygen in the blood. PFAS chemicals build up in your body over time and can weaken your immune system and affect liver function. Iron and manganese also exceed standards in county wells and can cause organ damage with long-term exposure.
Iron in county well water creates noticeable problems in your home. You will likely see rust-colored staining on sinks, toilets, and laundry. The water may have a metallic taste and smell. Iron can clog pipes and damage appliances over time. The good news is that Johnston County wells are soft, so you won't face the scale buildup and appliance damage that comes with extremely hard water.
We recommend getting your well tested with a comprehensive panel since multiple contaminants exceed health standards in this county. Your well could have higher or lower levels than what is common here, and testing is the only way to know what is actually in your water. A comprehensive metals and PFAS panel typically costs $200 to $400. Treatment options like activated carbon filters and reverse osmosis systems can address these specific 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 ⓘ |
|---|---|---|---|---|---|
| PFOS ⓘ municipal | 60 | 63% | Moderate | High | |
| PFOA ⓘ municipal | 60 | 55% | Moderate | High | |
| Iron | 137 | 43% | High | High | |
| Manganese | 137 | 34% | High | High | |
| Nitrate | 101 | 6% | High | Moderate | |
| PFHxS ⓘ municipal | 60 | 2% | Moderate | Low | |
| Fluoride | 99 | 1% | Moderate | Low | |
| Sulfate | 128 | 1% | High | Low | |
| Chloride | 169 | 0% | High | Low | |
| HFPO-DA (GenX) ⓘ municipal | 60 | 0% | Moderate | Safe | |
| Nitrite | 9 | 0% | Low | Safe ⓘ | |
| PFNA ⓘ municipal | 60 | 0% | Moderate | Safe | |
| Hardness | 131 | — | High | Low | |
| PFBS ⓘ municipal | 60 | — | Moderate | Low | |
| pH | 170 | — | High | Low | |
| Sodium | 111 | — | 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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