Groundwater in Loudoun County contains manganese, iron, chloride, sulfate, radon, and PFOA and PFOS. Several of these contaminants exceed EPA health standards, so well owners should test their water.
The rock beneath Loudoun County is an Early Mesozoic basin filled with layers of shale, sandstone, and other sedimentary rock. As water moves slowly through these rocks, it dissolves iron and manganese naturally present in the minerals. Chloride and sulfate also occur naturally in these layers, and radon comes from radioactive decay within the rock itself. PFOA and PFOS are human-made chemicals that have entered some wells through past industrial activity and firefighting foam use.
Groundwater in this county is moderately hard, driven by dissolved minerals including calcium and magnesium from the rock layers. The shale and sandstone here release these hardness minerals as water passes through over time. Elevated iron is present in many wells across the county, another common feature of water passing through these same rock types.
Wells in Loudoun County exceed EPA health standards for chloride, iron, manganese, PFOA, PFOS, radon, and sulfate. Radon is a radioactive gas that enters groundwater and can damage your lungs over time. PFOA and PFOS are human-made chemicals that can affect your liver, thyroid, and immune system. Manganese at elevated levels can harm the developing brain in children. Chloride and sulfate at high concentrations can cause digestive problems in people with certain health conditions.
The moderate hardness in county wells can leave scale buildup inside pipes and appliances like water heaters and dishwashers, which shortens their lifespan. You may notice white or cloudy deposits on faucets and showerheads. Some people report a slightly bitter or mineral taste in their water.
Every well is different and your water could have higher or lower levels than what is common in the county. We recommend testing your well with a comprehensive metals and minerals panel to find out exactly what is present so you can treat it properly. A comprehensive panel typically costs between two hundred and four hundred dollars. Treatment options like activated carbon filters and radon removal systems can address multiple 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 ⓘ |
|---|---|---|---|---|---|
| Manganese | 17 | 35% | Moderate | High | |
| PFOA ⓘ municipal | 40 | 20% | Moderate | High | |
| Iron | 37 | 19% | Moderate | High | |
| PFOS ⓘ municipal | 40 | 12% | Moderate | Moderate | |
| Radon | 13 | 8% | Low | Moderate ⓘ | |
| Sulfate | 37 | 3% | Moderate | Low | |
| Chloride | 37 | 3% | Moderate | Low | |
| Uranium | 17 | 0% | Moderate | Low | |
| Nitrite | 25 | 0% | Moderate | Low | |
| PFHxS ⓘ municipal | 40 | 0% | Moderate | Low | |
| Nitrate | 27 | 0% | Moderate | Low | |
| PFNA ⓘ municipal | 40 | 0% | Moderate | Safe | |
| Fluoride | 37 | 0% | Moderate | Low | |
| HFPO-DA (GenX) ⓘ municipal | 40 | 0% | Moderate | Safe | |
| Lead | 7 | 0% | Low | Low ⓘ | |
| Hardness | 37 | — | Moderate | Low | |
| PFBS ⓘ municipal | 40 | — | Moderate | Low | |
| pH | 33 | — | Moderate | Low | |
| Sodium | 37 | — | 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.
* 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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