This paper compares empirical mass transfer data--collected from over 90 pilot studies and full-scale air stripping systems--to that predicted by the Onda correlation. The data presented offers a very strong case for the use of onsite pilot testing and/or empirical data whenever possible. It highlights the need for liberal safety factors when theoretical designs are used. The information will, it is hoped, make engineers using canned softwater more aware of the limitations associated with such design programs. The study presented has been limited to 596 data points collected for three compounds that are among the prevalent organic compounds found in groundwater.