Isolation techniques with membrane-filtered potable water samples resulted in the isolation of potentially pathogenic high-catalase strains of Mycobacterium kansasii from 8 of 19 representative outlets in a small central Texas town. Mycobacterium gordonae was isolated from all samples, and Mycobacterium fortuitum was isolated from two samples. Data on chlorine levels are presented along with a possible explanation for the unusually high numbers of mycobacteria in these potable water samples. Findings suggest that water is a source of M. kansasii and may be an important link in the epidemiological picture of the disease.