Legionella 101



What is Legionella?

Legionella is a waterborne bacterial pathogen responsible for Legionnaires’ disease. Since its discovery, more than 60 species of Legionella have been identified. While there are many different species of Legionella that do not cause disease in humans, there is one species that causes the most problems, Legionella pneumophila, and is one we look out for most. Legionella pneumophila is divided into 16 serogroups, with Legionella pneumophila serogroup 1 being the most virulent, and responsible for approximately 80% of cases. Notably, the most common source of Legionella that leads to Legionnaires’ disease is the potable (drinking) water system (56%), while the second most common source is cooling towers (22%).


What is Legionnaires' Disease?

Legionnaires’ disease is a type of bacterial pneumonia caused by Legionella pneumophila, and occasionally by other species of Legionella. To contract Legionnaires' disease, two conditions must be met:

  1. A person encounters a device like a sink, shower, CPAP machine, or humidifier that contains growth of Legionella bacteria.
  2. Water droplets from that device are able to get into the lungs, like the mist from a shower.

Legionnaires' disease is particularly dangerous for the vulnerable, immunocompromised population. However, any person can contract it with the above conditions. People cannot develop Legionnaires’ disease from person-to-person contact. Symptoms include cough, shortness of breath, fever, muscle aches, and headaches. 

Legionnaires 1

The Water Drop:

What is Legionnaires' Disease?



What do I need to know?

What do I need to do?


The best way to prevent Legionella growth and a subsequent outbreak in your building is to:

  • Have a comprehensive Water Management Plan that identifies the areas in your building that are most vulnerable and susceptible to Legionella growth.
  • Have a routine testing schedule.
  • Have a company like IWC Innovations, who:
    • Handles the testing for you.
    • Interprets the testing results.
    • Offers recommendations to ensure that you are always minimizing your risk of a Legionella outbreak.



Trust the IWC Innovations Legionella Experts for all of your Legionella needs!