Sonoma County’s households often draw water from local aquifers, where groundwater travels through underground formations before reaching wells and taps. The water's journey can introduce naturally occurring elements, such as radon-222, a radioactive gas that dissolves into groundwater. This page helps homeowners in Sonoma County understand regional radon data from government testing and choose between two technical approaches for addressing radon in their water supply.

Interpreting the Sonoma County Aquifer Radon Median and Range

The U.S. Geological Survey sampled 42 wells in Sonoma County aquifers from April to August 2012, collecting 47 radon-222 results. The median radon level across these wells was 520.0 picocuries per liter (pCi/L), with a range from 10.0 to 16,700.0 pCi/L. This means that half the sampled wells had radon levels below 520.0 pCi/L, and the other half above, and individual wells varied widely. Understanding this range helps residential water users appreciate how radon concentrations can fluctuate naturally in this region's aquifer.

When Radon Is the Concern, Not Other Common Issues

Radon in water differs from common water problems such as mineral hardness or bacterial contamination. Unlike hardness, which causes scaling, or bacteria that may affect health directly, radon is a radioactive gas originating from natural decay of uranium in rock and soil. Unlike aesthetic issues like odor or taste, radon’s effect is linked to its radioactive properties, not sensory qualities. Recognizing this distinction can guide homeowners to evaluate whether radon specifically requires treatment versus other water quality concerns.

Understanding 'Detected,' 'Median,' and 'Range' in Radon Sampling Records

• Detected: Every sample from the Sonoma County aquifer showed measurable radon-222. Detection indicates the instrument measured radon but does not imply any safety or legal violation.
• Median: The middle value (520.0 pCi/L) representing a typical concentration among sampled wells, not a limit or threshold.
• Range: The span from lowest to highest (10.0 to 16,700.0 pCi/L), illustrating natural variability.

None of the samples were above federal thresholds for radon in water, indicating compliance with current regulations for public and private water sources in the area. However, individual well testing is necessary to know specific household water radon levels.

How the C-Series Radon in Water Filter Treats Radon in Residential Water

The C-Series System addresses radon dissolved in water by removing radon gas during water flow through a specialized filtration medium. This technology reduces radon to levels below detection in water supplies, helping minimize exposure from household water usage. The system ships ready to configure for point-of-entry use, making it suitable for treating all water entering a home, but it does not rely on chemical additives or changing water chemistry.

Which Household Fixtures and Processes Are Affected First by Radon

Radon gas is most concerning where water-to-air transfer occurs, such as during showering, cooking, or laundry, as radon can be released into indoor air. Fixtures involving aeration release more radon from water, increasing inhalation potential. Therefore, addressing radon in whole-house water supply impacts appliances that aerosolize water most, reducing overall indoor radon exposure.

What to Record Before Requesting Treatment Advice

• Obtain a recent water test specifically measuring radon concentration from your household well.
• Note well depth and year of construction, if known.
• Record household water usage patterns and the number of occupants.
• List any existing water treatment or filtration devices in use.
• Gather information on any radon levels reported in nearby wells or community water supplies.

Accurate, specific data from your household water source is essential for choosing between treatment approaches effectively.

This page walked through understanding Sonoma County’s regional radon sampling data and how to interpret median and range values for homeowners. By distinguishing radon’s unique characteristics and knowing what data to collect, residential users can make informed choices about water treatment technologies such as the C-Series Radon in Water Filter.

Where this information comes from

Source: USGS groundwater sampling. Sampled 2012-08-23. 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 aquifer (Sonoma County): 47 results from 42 wells, median 520.0 pCi/L, range -10.0-16700.0 pCi/L; none above any federal threshold