A device was developed for the collection, containment, and bubbling of radon from groundwater samples to facilitate concentration measurements in the field without the need for fragile glassware. Wellwater supplies were collected in high-potential areas of New York State in a comparison of the device with traditional methods (liquid scintillation and laboratory-based Lucas-cell counters). Waterborne radon levels to 4100 Bq L−1 reveal the potential contribution to indoor air from everyday water use in a home, as levels of 1500 Bq L−1 contribute about 150 Bq m−3 (the EPA-recommended limit) to indoor-air radon levels. With a Geographic Information System (GIS), spatial coordinates from each site are used to correlate concentrations with bedrock geology.