The survival of Mycoplasma hominis, Mycoplasma salivarium, Mycoplasma pneumoniae, and Ureaplasma urealyticum in water and at elevated temperatures is a cause for concern. These microorganisms are pathogens. Some are implicated in serious genitourinary tract infections in men and women resulting in significant perinatal mortality and morbidity; others can cause respiratory tract infections. M. hominis has been implicated in wound infections, osteomyelitis, and infections of the heart valve.Because these microorganisms are pathogens, their survival in a closed water system has relevance to the well-being of crew members in an enclosed space. Consideration must be given to the elimination of these bacteria during recycling of water.