This article discusses a pilot‐scale study on the influence of 1‐10 ppm alkyl benzene sulfonate (ABS) on the underground travel of biologic forms such as the coliform organism. The tests were confined to continuous‐ flow, water‐saturated columns 6 in. in diameter and containing 10 ft of sand. The principal findings over an 18‐month test period were: ABS at 1‐10 ppm did not have a significant influence on the movement of coliform organisms through homogeneous sands that were saturated with water; coliform organisms traveled much more slowly than salt or ABS, they did not penetrate much beyond 6 ft. in 417 days when the water was moving 0.4 ft/day; doubling the rate of water movement to 0.8 ft/day merely reduced the coliform arrival time at 4 ft from 114 days to 82 days; doubling the effective size of the sand from 0.2 mm to 0.4 mm did not alter the arrival time of coliform organisms through 2 ft. of sand; and, no change in radioactive ABS35 concentration resulted from the presence and action of coliform organisms and a few other biological forms.