Nontuberculous mycobacteria are everywhere in the environment, including water (both natural sources and treated tap water) and soil. Doctors and scientists believe that some patients become infected with NTM from inhalation of mycobacteria that become aerosolized by showers, kitchen sink sprayers, indoor pools, hot tubs, or from refrigerator ice makers. For this reason, if you have an underlying condition that might make you susceptible to NTM infection, you may wish to speak to your doctor about the advisability of bathing in a tub rather than showering.
Some patients may become infected with NTM from inhalation of mycobacteria naturally existing in potting soil, through activities like gardening. Many doctors and scientists believe NTM lung infection is not just due to exposure to the bacteria in the environment but also because of host vulnerability – some people are more predisposed to infection.