Mycobacterium avium is capable of an adaptive, reversible response to high-temperature survival depending on its growth temperature. Trehalose concentrations of M. avium cells grown at 42 °C were significantly higher compared to those of cells grown at 25 °C. Further, the survival of cells of M. avium grown at 42 °C and exposed to 65 °C were significantly higher than the survival of cells grown at 25 °C. This adaptive response to growth temperature may play a role in the persistence of M. avium in premise plumbing.