Highest-Risk Sources for Community-Acquired Legionnaires’ Disease 1. Cooling Towers Cooling towers are suspected to be the largest source of community-acquired Legionnaires’ disease because they produce significant aerosol plumes that can travel anywhere from a few hundred feet to several miles away, exposing entire local areas to Legionella. Risk factors for Legionella: Large aerosol produced Wide drift range of the aerosol Warm operating temperatures Poor maintenance of biofilm growth Potential to infect many people in a short period of time 2. Large-Building Plumbing Systems Large-building plumbing (potable water) systems are responsible for a large proportion of sporadic community-acquired cases, with buildings like apartments, hotels, office buildings, and older mixed-use buildings contributing to outbreaks. Risk factors for Legionella: Stagnation and dead legs in piping Warm recirculation temperatures (95–115°F zones) Low municipal disinfectant residuals Multiple building levels Age of the building Complex plumbing system with variable flow and usage 3. Spas and Hot Tubs Hot tubs produce a high rate of illness per exposed individual and are common sources of smaller but intense outbreaks, especially in hotels, cruise ships, and gyms. Risk factors for Legionella: High temperatures that are ideal for Legionella Continuous heavy aerosol generation Rapid disinfectant depletion from organic load Inadequate maintenance of the hot tub or spa How to Reduce Your Risk for Legionella Work with an independent Legionella engineering company that can provide Legionella training and consultation Have a water management plan Consider secondary disinfection options to prevent or remediate Legionella Contact Legionella Control Systems to reduce your risk of Legionella with expert root cause analysis and remediation. Request Proposal Contact Us
