The U.S. Geological Survey’s groundwater sampling in St. Charles County, Missouri, aquifer 110QRNR, shows arsenic was detected consistently in wells sampled between 2011 and 2015. All 13 results from 11 wells, ranging from 8 to 43 feet deep, reported arsenic concentrations from 0.26 to 18.5 micrograms per liter. None of these measurements exceeded federal arsenic thresholds, indicating regional groundwater in this aquifer does not record violations based on current federal standards.
How Sample Depth Affects What You Should Expect for Arsenic in Your Water
The sampled wells’ depths varied from shallow (8 feet) to moderate depth (43 feet). Arsenic concentration in groundwater can depend on factors including depth, soil composition, and local geology. Shallow wells may show different arsenic levels than deeper ones because arsenic can leach from surface soils or bedrock layers differently. Therefore, a well’s depth is an important factor to consider when evaluating potential arsenic presence, but it does not alone determine arsenic levels in your specific water supply.
What a Certified Laboratory Arsenic Test Report Includes and How to Interpret It
Testing your household water through a certified laboratory provides a precise measurement of arsenic concentration. Such reports typically list arsenic in micrograms per liter (µg/L), alongside detection limits and the reporting limits of the test method. A concentration below the detection limit means arsenic was not measurable, while a result below the federally established threshold indicates compliance with safety standards. Understanding the numerical value helps decide if water treatment is warranted, but it is specific to your water supply, not inferred from regional data.
Example: Interpreting Median and Range Values from Regional Data as a Homeowner Would
In St. Charles County’s aquifer 110QRNR, the median arsenic concentration in sampled wells was 0.53 µg/L, with values ranging from 0.26 to 18.5 µg/L. This suggests that half the measured samples were near or below 0.53 µg/L, while some wells showed higher levels up to 18.5 µg/L. Since all values fall below federal limits, these findings indicate low to moderate arsenic presence within the aquifer but do not predict exact household water arsenic levels without direct testing.
Consequences of Leaving Arsenic Untreated Over the Long Term
Arsenic is a naturally occurring element that can accumulate in groundwater. Chronic long-term consumption of water with elevated arsenic concentrations may pose health concerns according to public health research. Without monitoring and addressing arsenic presence in well water, households risk exposure over years. While regional data shows no exceedances here, individual well water testing is important to detect any local variations that could require treatment.
Assessing Treatment Capacity Relative to Your Household Water Use
Once your water arsenic level is established through testing, choosing treatment equipment involves matching capacity to daily household demand. Treatment systems designed for arsenic typically have rated flow capacities and filter media volumes suited for specific usage levels. Selecting a system sized appropriately for your water usage ensures effective arsenic reduction without frequent maintenance. The C-Series Arsenic Filter ships ready to configure, adapting to household demand for reliable treatment.
Important: Regional sampling data reflects general conditions in St. Charles County’s aquifer 110QRNR and cannot replace individual water testing. Arsenic concentrations vary with well characteristics and location. Only a certified laboratory test of your own water supply confirms the presence and level of arsenic requiring attention.
Where this information comes from
Source: USGS groundwater sampling. Sampled 2015-08-12. 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 110QRNR aquifer (St. Charles County): 13 results from 11 wells, median 0.53 ug/L, range 0.26-18.5 ug/L; none above any federal threshold