What does a certified lab test tell me about uranium or radium in my household water?

A certified laboratory measures uranium concentration in your water sample by detecting the amount of uranium in micrograms per liter (ug/L). The test report will show the uranium concentration detected, or indicate if the level is below the laboratory's reporting limit. Understanding these values helps you determine if uranium is present in your well water and at what approximate level.

It is important to remember that only your specific water test establishes the uranium content of your household water. Regional sampling data, such as that collected by the U.S. Geological Survey in Fresno County, show what levels are found across multiple wells but do not define your water's exact quality.

How should I compare the uranium findings in Fresno County with neighboring counties without misinterpreting the data?

Uranium levels recorded in Fresno County aquifers range widely. In the local area, groundwater samples from 80 different wells taken between December 2013 and November 2024 showed uranium levels from 0.041 ug/L up to 250.0 ug/L, with a median of 7.24 ug/L. These measurements were taken at various depths from 100 to 3259 feet but none exceeded any federal uranium limits.

Comparing this with data from nearby counties should be done cautiously. Variations can reflect differences in geology, well depth, and sampling methods rather than a uniform risk or problem. Regional data sets help establish general background levels but do not replace a specific test of your own water source.

How do uranium and radium typically enter the groundwater in Fresno County?

In Fresno County, uranium and radium naturally occur in mineral deposits underground. Over time, these radioactive elements can dissolve from rocks and soils into the aquifer water. Groundwater flow and geochemical conditions influence how much uranium or radium is released.

This natural leaching process means private wells drawing from the aquifer could contain detectable uranium, although the range and concentrations vary widely. Surface water sources and municipal systems may be less directly affected depending on their water source and treatment.

What information should I have ready before seeking advice about uranium or radium water treatment?

• The specific uranium or radium concentration values from a certified lab test of your household water
• The depth and source type of your well or water supply
• Average daily water usage in your household to estimate treatment capacity needed
• Any seasonal or historical water quality data you have collected
• Local groundwater conditions or aquifer information from official sources

Having these details enables tailored recommendations and helps identify the appropriate scale and type of treatment technology to address uranium or radium if needed.

How do seasonal or multi-year variations appear in the uranium data for Fresno County?

The U.S. Geological Survey sampling spanned over a decade, from late 2013 through late 2024, capturing a robust range of uranium concentration measurements across multiple wells. This long-term data reflects potential fluctuations in uranium levels caused by changing groundwater flow, aquifer recharge, and geochemical conditions over time.

Such variation means a single test date might not reveal the full picture. Regular testing or trend monitoring can better establish how stable or variable uranium levels are in your water source.

How do public water system records differ from private well testing in what they establish for uranium and radium?

Public water systems typically follow regulatory monitoring requirements and provide water quality reports that show compliance with health standards. In Fresno County, no federal uranium thresholds were exceeded in the sampled wells, supporting a record of compliance for community water supplies using the aquifer.

Private well owners, however, must conduct individual testing since their water source and depth can vary significantly from public systems. Private well testing results are the only definitive measure of uranium or radium concentration for a household's water and are critical for making informed treatment decisions.

What should I not conclude from area uranium data in Fresno County?

Regional sampling indicates a range of uranium concentrations does exist in the aquifer, but the presence of uranium measured in other wells near you does not mean your household water contains the same levels, or that it is unsafe. None of the sampling results in this area exceeded federal uranium health thresholds, and detection alone is not a violation or proof of risk.

Choosing treatment should be based on your own certified water analysis, not regional averages or extremes. The documented C-Series Uranium & Radium System ships ready to configure for use in homes and provides effective reduction of uranium, supporting safe household water management where needed.

Where this information comes from

Source: USGS groundwater sampling. Sampled 2024-11-09. 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 Uranium in the aquifer (Fresno County): 109 results from 80 wells, median 7.24 ug/L, range 0.041-250.0 ug/L; none above any federal threshold