The survival of Vibrio cholerae non-O1 was investigated in sterile and untreated river water. The essential nutrients for growth of the organism were also investigated using a compound medium. V. cholerae non-O1 was shown to increase in autoclaved sterile river water, but did not increase in filtrated river water, and starting with an initial number of 10(6) CFU/ml organism, the organism could not be isolated from untreated river water after day 10. The growth or survival of the organism was also studied with filtrated river water to which all essential nutrients except one was added. In this water, V. cholerae non-O1 did not increase when either phosphate or a carbon source was not present. These results indicate that V. cholerae non-O1 can survive in river water by taking nutrients for growth from solutes and particle matter in the river water.