When you receive a laboratory test report for radon in your household water, you will see a measurement expressed as picocuries per liter (pCi/L), indicating the amount of radon-222 present. Understanding what these numbers mean requires context about local groundwater conditions and sampling data.
If you want to understand how many local samples support radon figures for your area
Umatilla County’s aquifer N600CMBPLV was sampled by the U.S. Geological Survey during July and August 2016. Three separate wells, ranging from 502 to 1116 feet deep, were tested. All three detected radon-222 with values ranging from 110.0 to 450.0 pCi/L and a median concentration of 203.0 pCi/L. Despite this detected presence, none of these results exceed any federal threshold for radon in drinking water.
It is important to note that these results come from a very small number of wells within this aquifer region. Consequently, while they provide meaningful regional insight, they cannot substitute for an individual home's water test to precisely identify radon levels in your water supply.
If you observe certain faucets, showers, or water appliances first affected by radon
Radon gas dissolved in groundwater is released into air whenever water is agitated or heated. Fixtures such as showers, hot water heaters, and dishwashers typically release radon as water flows through them, contributing to indoor air concentrations. Monitoring these points can help you understand where radon exposure may be occurring first. Confirming radon levels in water at these points requires proper testing, as household water use patterns influence exposure.
If well depth or water source type influences what you should expect regarding radon levels
Because the sampled wells in Umatilla County reached depths from just over 500 feet to more than 1100 feet, radon concentrations can vary within the aquifer at different depths. Generally, deeper wells may tap groundwater with different radon levels compared to shallow sources. Differences in geology along the aquifer and well construction can further affect radon presence. To know the radon level in your home’s water, testing of your specific source remains necessary, as regional figures do not predict individual wells.
If you are trying to understand the median and range found in the government record
The median detected radon level of 203.0 pCi/L suggests that half of sampled wells recorded concentrations below this value and half above, within the observed range of 110.0 to 450.0 pCi/L. This provides a frame of reference if your own water test shows a similar or different concentration. The presence of radon in these samples confirms it is naturally present in the aquifer, but not necessarily at harmful or legally unsafe levels at any individual site. Your household’s actual measurement depends on your well and local conditions.
If you want to understand how radon enters groundwater in Umatilla County’s aquifer
Radon-222 forms naturally from the radioactive decay of uranium found in soil and rock beneath Umatilla County. It moves from surrounding materials into groundwater through fractures and porous spaces. Because radon is a gas, it can dissolve into groundwater and then be carried in wells drilled into these aquifers. The extent of radon in groundwater depends on local uranium concentrations, rock permeability, and groundwater flow patterns. These natural processes explain the detections found in the sampled wells.
To reduce radon levels in household water after measuring your own water’s concentration, the Autotrol Radon in Water Filter ships ready to configure for home use. This system addresses radon presence specifically and can be incorporated based on your household’s measured demand, providing a documented approach to managing radon in residential water supplies.
Where this information comes from
Source: USGS groundwater sampling. Sampled 2016-08-10. 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 N600CMBPLV aquifer (Umatilla County): 3 results from 3 wells, median 203.0 pCi/L, range 110.0-450.0 pCi/L; none above any federal threshold