There are several methods used to treat water systems for Legionella, including thermal treatment (raising water temperatures to kill bacteria), chemical treatment (using disinfectants like chlorine, monochloramine, or chlorine dioxide), and physical methods (such as UV light or copper-silver ionization). Regular monitoring and maintenance are also critical to ensure the effectiveness of these treatments​.

The frequency of testing for Legionella depends on the specific water system and its risk factors. Generally, high-risk systems, such as those in healthcare facilities or large buildings with complex plumbing systems, should be tested quarterly or at least twice a year. Lower-risk systems may be tested annually. Regular testing helps detect and address any issues before they lead to significant contamination​.

A comprehensive water management plan for controlling Legionella should include the following components:

• Risk Assessment: Identify areas where Legionella could proliferate.
• Control Measures: Implement methods to control the growth of Legionella, such as maintaining appropriate water temperatures and disinfectant levels.
• Monitoring: Regularly test water systems for Legionella and other indicators of water quality.
• Documentation and Communication: Keep detailed records of all maintenance, testing, and corrective actions. Ensure all relevant personnel are informed and trained on Legionella control measures.
• Emergency Response: Develop a plan for responding to suspected or confirmed Legionella outbreaks​.