Understanding Detected, Median, and Range in Arsenic Sampling

Detected means measurement confirmed presence within testing limits

The U.S. Geological Survey (USGS) detected arsenic in most samples taken from wells in Otero County's aquifer S100RIOGRD. Detection shows an instrument measured arsenic but does not imply a violation or unsafe level for your well.

Median reflects the middle value of all detected arsenic concentrations

The median arsenic concentration from seven samples collected between 2020 and 2022 is 0.32 micrograms per liter (µg/L). This value helps summarize typical arsenic levels across sampled wells in the area.

Range indicates variability between samples

The recorded arsenic values ranged from 0.2 to 0.46 µg/L in wells between 250 and 995 feet deep, representing the lowest and highest measurements detected within this sample set.

Sample Number and Well Depth Considerations

Data is based on seven results from five wells

The USGS results reflect a relatively small sample size, which may limit the ability to generalize for all wells in the aquifer. Results offer useful insight but do not establish conditions in any individual well.

Sampled wells vary significantly in depth

Wells tested ranged from 250 to 995 feet deep, showing arsenic measurements at different depths of the aquifer. Arsenic concentrations can vary with depth and location.

How Plumbing Materials and Age Affect Arsenic Presentation

Plumbing may influence arsenic levels in tap water

The materials and age of your plumbing system can affect how arsenic from source water appears in household taps. Corrosion or reactions in pipes might alter concentrations or form deposits.

Source water quality differs from what reaches fixtures

It is important to distinguish between arsenic present in groundwater and any changes caused by plumbing before concluding about household water safety or quality.

Interpreting Median and Range as a Homeowner

The median value suggests typical conditions in sampled wells

For homes drawing from aquifer S100RIOGRD, 0.32 µg/L arsenic provides a central estimate of concentration but does not predict individual well levels.

The observed range shows some variation but remains below federal limits

Measured arsenic values did not exceed any federal thresholds in the samples, indicating no detected samples in this data set surpassed regulatory limits for arsenic.

Impact of Household Size and Property Use on Arsenic Considerations

Larger households may consume more water, affecting treatment needs

Water treatment equipment should match usage, as arsenic concentrations in source water do not change with household size, but larger volumes could require greater system capacity.

Second homes or seasonal properties need their own water testing

Water quality can vary over time and by location. Homes not used year-round should perform specific testing before assuming water conditions are constant.

What Certified Laboratory Testing Reports and How to Use It

Laboratory reports provide your well’s unique arsenic level

Only a certified test of your household water can confirm the actual arsenic concentration in your well or tap, as area data cannot substitute for individual testing.

Reports include detected value, detection limit, and often compare to standards

Understanding the lab’s terms, units, and reported results helps homeowners determine if treatment is advisable.

Final Step: Confirming Your Water’s Arsenic Level

Order a certified laboratory test specifically for arsenic in your household water to know your actual arsenic concentration. If the result approaches or exceeds levels of concern, considering the C-Series Arsenic Filter may help address it. This system ships ready to configure to suit your home’s needs.

Where this information comes from

Source: USGS groundwater sampling. Sampled 2022-09-14. 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 S100RIOGRD aquifer (Otero County): 7 results from 5 wells, median 0.32 ug/L, range 0.2-0.46 ug/L; none above any federal threshold