Real Estate Manager Checklist: Legionnaires' Disease

Legionnaires’ disease is a potentially fatal form of pneumonia contracted by inhaling tiny droplets of water containing the Legionella bacteria.

Refer to the following checklist for suggestions on addressing the risk of the Legionella bacteria at your properties.

Possible Sources of Legionella

  • Cooling towers, evaporative condensers, and fluid coolers
  • Domestic hot-water systems
  • HVAC systems, humidifiers, and misters
  • Decorative fountains
  • Spas and whirlpools
  • Stagnant water systems, including fire sprinkler systems, eye washes and safety showers.


  • Eliminate conditions in water sources that promote the growth of Legionella
    • Stagnant water
    • Temperatures between 68º - 122ºF (20º - 50ºC)
    • pH between 5.0 and 8.5
    • Micro-organisms including algae, flavobacteria, and Pseudomonas
  • Review maintenance records on water systems including temperature checks of domestic water, visual and physical checks of cooling towers, and reports of water-quality assessment and chemical treatment
  • Record the maximum temperature of water at faucets connected to each water heater
  • Examine the water temperature and the potential for stagnation of storage tanks
  • Evaluate condition of cooling towers, evaporative condensers, and fluid coolers for biofilm growth, scale buildup, and turbidity
  • Note the location of the fresh-air intakes of the building's air-handling units relative to water sources such as the cooling towers
  • Identify occurrences of stagnant water, such as storage tanks or unused plumbing pipe sections ("dead legs") or infrequently used faucets
  • Check for cross-connections between domestic and process water systems and note the condition and type of back-flow prevention devices


  • Avoid or abandon equipment that creates mists or sprays
  • Avoid dead-ends and stagnant corners in pipework
  • Design holding tanks for easy cleaning and draining
  • Maintain records of testing, maintenance, and prevention; monitor results
  • Adopt a comprehensive water treatment program
  • Clean and disinfect cooling towers regularly
  • Regularly inspect, clean, and disinfect HVAC
  • Maintain domestic water heaters at 140ºF (60ºC)
  • Avoid locating cold water storage tanks in sunlight; insulate if necessary
  • Drain and clean whirlpools and filters regularly, control pH levels


  • Educate residents/tenants on Legionnaires’ disease, including potential symptoms and what to do if they think they may be infected
  • Advise residents/tenants about the assessment and prevention measures you are taking
  • Notify residents/tenants of contamination if there is an outbreak
  • Consider the age of residents/tenants before raising the water temperature. If you raise the temperature, warn residents/tenants about the risk of burns and scalding.



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