Prevention is aimed at improving the design and maintenance of cooling towers and plumbing systems. The goal is limiting the growth and aerosolization of Legionella organisms. Hyperchlorination tends to be ineffective at disinfecting the water supply. Copper-silver ionization, super heating, and monochloramine disinfection are newer methods of controlling and eliminating growth of this bacteria.During outbreaks, health department investigators seek to identify the source of disease transmission and recommend appropriate prevention and control measures, such as decontamination of the water source.Detailed guidelines for the prevention of Legionnaires' disease both in hospitals with no identified cases ("primary prevention") and in hospitals with reported cases ("secondary prevention") have been published and are available in the U.S. from the Centers for Disease Control and Prevention.