Does usage of a well impact a radon test of well water?

Question

Our well was unused for 6 months during a home renovation. The water was then tested and the radon level came back at 8300 pCi/L. Could this high level just be a function of lack of usage? i.e. the radon accumulated in the well over time to reach high levels that otherwise would not have been achieved had there been steady usage of well water.

Answer 1

Yes, radon has very low solubility in water. With agitation and exposure to the atmosphere most dissolved radon is outgassed to the atmosphere, so inactivity in a water well is likely to allow the radon concentration in the water to increase. The amount of radon in groundwater is related to the uranium content of the rock the water is found in, the distribution of the ground water relative to that rock, and the groundwater flow patterns. However, the radon levels of the active well may be sustained depending on the type of aquifer rock.
http://enhs.umn.edu/hazards/hazardssite/radon/radonintro.html

The U.S. Environmental Protection Agency's recommended Maximum Contamination Level is 300 pCi/L. You may want to consider some type of splash box and aeration of your water to remove the radon.
http://www.informaworld.com/smpp/content~content=a713629825~db=all

Answer 2

In a very shallow well, (surface ground water), possibly.
For a deep well, probably not.