What does a certified laboratory test report about radon in Anne Arundel County groundwater?
Certified laboratory testing for radon-222 in groundwater from Anne Arundel County, specifically from aquifer 125AQUI, reports concentrations in picocuries per liter (pCi/L). The U.S. Geological Survey conducted sampling at four separate wells between June 2011 and August 2017. The radon-222 levels ranged from 94.0 to 240.0 pCi/L, with a median concentration of 221.0 pCi/L. The tests detected radon in all four samples, though detection alone does not indicate any violation or safety concern. Results reflect measurements at wells 70 to 280 feet deep and are representative of this area, not specific to any individual household well.
What do these radon measurements mean compared to federal standards, and what do they not indicate?
None of the radon-222 results from these Anne Arundel County samples exceeded any federal threshold for radon in drinking water. This means, according to the federal record, radon levels in this aquifer have been found below the regulatory maximum. However, detection and levels measured do not guarantee that an individual household’s water will match these numbers or be free from radon concerns. Additionally, these results do not imply that the radon is unsafe at the detected levels, only that radon was present. Proper testing of your own household's water is necessary to confirm your specific radon concentration.
How do sample depth and well characteristics affect expectations about radon levels?
Well depth and water source can influence radon concentration in groundwater. The sampled wells in this area ranged from 70 to 280 feet deep, demonstrating some variation in radon measurements within this depth range. Generally, deeper wells may have different radon levels than shallower ones, but this is not a universal rule. The geological formations tapped by a well and aquifer characteristics will also affect radon presence. Hence, understanding your own well’s depth and source type is important in interpreting radon risk and deciding on any treatment approach.
Why do aesthetic secondary standards differ from health-based limits for radon in water?
For radon-222, federal health-based standards set maximum recommended levels designed to limit health risks. In contrast, aesthetic secondary standards govern factors like taste, odor, and staining in water, which do not apply to radon. Radon’s presence in water is odorless, tasteless, and colorless, so aesthetic standards are not relevant for this constituent. Differentiating between these standards helps clarify that measured radon levels should be evaluated primarily against health-based limits rather than aesthetic guidelines.
How can Anne Arundel County’s radon water record be compared to neighboring counties without overinterpretation?
Radon levels vary regionally based on geology and aquifer characteristics. The USGS sampling in Anne Arundel County shows radon detections in all wells tested, with moderate concentrations. Neighboring counties may have differing radon statistics reflecting local conditions. Comparing these area-wide measurements can provide context but should not lead to assumptions about any single well’s radon content. Each household should rely on its own water testing rather than regional data alone to determine radon presence and treatment needs.
If your existing water equipment struggles to maintain satisfactory radon reduction given your measured levels, the Autotrol Radon in Water Filter ships ready to configure for your household. Designed to address radon-222 in water, it can help manage demand according to your own testing results from a certified laboratory.
Where this information comes from
Source: USGS groundwater sampling. Sampled 2017-08-29. These figures describe groundwater sampled in this area. They are not a test of any individual private well - only a test of that well can establish its own water.
On record: U.S. Geological Survey sampling of Radon-222 in the 125AQUI aquifer (Anne Arundel County): 4 results from 4 wells, median 221.0 pCi/L, range 94.0-240.0 pCi/L; none above any federal threshold
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