Hospital engineers often go to guidance documents for help in preventing Legionnaires' disease. While advisory documents from health authorities and professional societies provide guidelines for approaches to prevention (Table 1), (1) a consensus opinion for prevention of this disease does not exist. (2) The lack of consensus stems from several unresolved issues: * Many of the recommendations are not evidence-based and, if followed, may not result in control and prevention of hospital-acquired Legionnaires' disease;
