Understanding Detected, Median, and Range in Arsenic Sampling Records
Detected means actual measurement above reporting limits
In groundwater testing for arsenic in Hunterdon County's aquifer 227PSSC, all 32 samples from 13 wells showed detectable arsenic levels. Detection indicates the presence of arsenic measured by the testing method used, not a violation or safety issue.
Median represents the middle value within the sample set
The median arsenic concentration found was 4.4 micrograms per liter (µg/L), meaning half of the samples measured below this and half above. This helps summarize typical conditions but does not reflect any individual well.
Range denotes lowest to highest values measured
Arsenic levels in samples varied from 0.15 to 24.7 µg/L across wells between 37 and 555 feet deep. The range shows the variability in arsenic presence in this aquifer but does not apply as a prediction for any one home’s water.
How the Measured Range Compares to Federal Standards
No sample exceeded federal arsenic limits
The US Environmental Protection Agency (EPA) sets a federal standard for arsenic in drinking water at 10 µg/L. Although some samples approached but did not exceed this benchmark, none surpassed it during this monitoring period.
Detection above zero is not an exceedance
Finding arsenic at any measurable concentration is common in groundwater but does not mean the water violates safety standards or is unsafe to use.
Sampling variability does not establish your household’s water quality
These results represent tested wells in Hunterdon County aquifer 227PSSC. Your household water may differ and requires individual testing to confirm its arsenic concentration.
Household Indicators Related to Arsenic in Water
Arsenic presence does not produce taste, smell, or color changes
Unlike some other water issues, arsenic does not cause noticeable changes such as discoloration or odor. Invisible arsenic can only be identified through laboratory analysis.
Signs of water quality problems often come from other contaminants
Discolored water, staining, or off tastes typically indicate issues other than arsenic and should prompt testing for those concerns as well.
Testing is necessary to confirm arsenic concerns
Because arsenic lacks sensory clues, a certified water test is essential to identify its presence and level in your household water.
Additional Questions for Commercial or Industrial Operators Compared to Households
Volume and treatment capacity needs
Commercial users must assess water demand and treatment scale, while households generally focus on point-of-entry treatment solutions.
Regulatory compliance complexity
Industrial and commercial entities face more rigorous reporting and compliance requirements beyond typical household considerations.
Specific process water quality standards
Businesses may require arsenic limits tailored to their industrial processes, which are different from residential drinking water standards.
Differentiating Arsenic from Other Commonly Confused Water Issues
Arsenic is a dissolved metalloid, not related to iron or manganese staining
Water problems with reddish or black stains usually arise from iron or manganese, not arsenic.
Arsenic does not cause hardness in water
Hardness comes from calcium and magnesium minerals, which are unrelated to arsenic presence or removal.
Arsenic testing requires specific analytical methods
Standard water tests for pH, hardness, or iron do not measure arsenic. Separate laboratory analysis is necessary.
This information reflects sampling of wells in Hunterdon County’s aquifer 227PSSC collected from May 2010 through January 2026 by the U.S. Geological Survey. For detailed data, refer to their groundwater monitoring records.
To address arsenic effectively, a Fleck Arsenic Filter system ships ready to configure for residential use, offering a documented solution tailored to remove arsenic from household water supplies.
Where this information comes from
Source: USGS groundwater sampling. Sampled 2026-01-22. 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 Arsenic in the 227PSSC aquifer (Hunterdon County): 32 results from 13 wells, median 4.4 ug/L, range 0.15-24.7 ug/L; none above any federal threshold
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