Well owners in Arlington County should be aware of three contaminants in their groundwater: manganese, iron, and chloride. All three are present at levels that exceed EPA health standards, so they deserve attention.
These contaminants come from the rock layers beneath Arlington County. Iron and manganese naturally dissolve from the sediment and rock in the Northern Atlantic Coastal Plain aquifer system when groundwater sits without oxygen. Chloride comes from road salt used during winter and from the natural saltwater that sits deeper in these aquifer layers.
Groundwater in Arlington County is hard, with elevated iron and manganese as the main drivers of its mineral character. These metals concentrate here because the sandy and clay layers of the coastal plain aquifer release them into water as it moves slowly underground. Hard water with high iron is common across wells in this county.
Wells in Arlington County commonly have chloride, iron, and manganese at levels that exceed EPA health standards. Chloride at high levels can be a concern for people with heart disease or high blood pressure. Iron and manganese can affect the nervous system with long-term exposure, and both pose particular risks to infants and young children.
County well water tends to be hard, which causes mineral buildup on fixtures and inside pipes and appliances. You may notice orange or brown staining in sinks and toilets, or a metallic taste in your water. Hard water can shorten the lifespan of water heaters and dishwashers by forcing them to work harder.
We recommend testing your well water with a comprehensive metals and minerals panel, which costs between $200 and $400. Every well in the county is different, and your well may have higher or lower levels than what is common here. Testing is the only way to know what is actually in your water so you can treat it properly. Water softeners and iron filters are common treatment options for these contaminants.
| Contaminant | Samples ⓘ | % Above MCL ⓘ | Distribution ⓘ | Confidence ⓘ | Risk ⓘ |
|---|---|---|---|---|---|
| Iron | 1 | 0% | Low | Safe ⓘ | |
| HFPO-DA (GenX) ⓘ municipal | 8 | 0% | Low | Safe ⓘ | |
| Chloride | 1 | 0% | Low | Low ⓘ | |
| Fluoride | 1 | 0% | Low | Safe ⓘ | |
| Sodium | 1 | — | Low | Low ⓘ | |
| PFBS ⓘ municipal | 8 | — | Low | Low ⓘ | |
| Hardness | 1 | — | 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.
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