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CDC Legionella toolkit

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4 DEVELOPING A LEGIONELLA WATER MANAGEMENT PROGRAM Introduction to Legionella Ecology Legionella pneumophila Where can Legionella grow and/or spread? Legionella can grow in many parts of building water systems that are continually wet, and certain devices can then spread contaminated water droplets. Examples include: • • • • • • • • • • • • • • • • • • Hot and cold water storage tanks Water heaters Water-hammer arrestors Expansion tanks Water filters Electronic and manual faucets* Aerators Faucet flow restrictors Showerheads* and hoses Pipes, valves, and fittings Centrally-installed misters*, atomizers*, air washers*, and humidifiers* Nonsteam aerosol-generating humidifiers* Infrequently used equipment, including eyewash stations* Ice machines* Hot tubs* Decorative fountains* Cooling towers* Medical devices* (such as CPAP machines, hydrotherapy equipment, bronchoscopes) *These devices can spread Legionella through aerosols or aspiration Legionella is found naturally in freshwater environments, like lakes and streams, but generally the low amounts in freshwater do not lead to disease. Legionella can become a health problem in building water systems. To pose a health risk, Legionella first has to grow (increase in numbers). Then it has to be aerosolized so people can breathe in small, contaminated water droplets. Factors external to buildings that can lead to Legionella growth 6 6 6 Construction: Vibrations and changes in water pressure can dislodge biofilm and free Legionella into the water entering your building. Water main breaks: Changes in water pressure can dislodge biofilm and free Legionella into the water, while dirt and other materials can be introduced into the water and use up disinfectant. Changes in municipal water quality: Changes in water quality can increase sediment, lower disinfectant levels, increase turbidity, or cause pH to be outside recommended ranges. Changes in disinfectant type can impact how you should monitor your program.

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