Legionella in Health Care Settings

Legionella is a type of bacteria found naturally in freshwater environments, like lakes and streams. It can become a health concern when it grows and spreads in human-made water systems like:

  • Showers and faucets
  • Cooling towers (air-conditioning units for large buildings)
  • Hot tubs
  • Decorative fountains and water features
  • Hot water tanks and heaters
  • Large plumbing systems

Home air-condition units do not use water to cool the air so they are not a risk for Legionella growth.

  1. Need to Know
  2. Expectations
  3. Resources
  4. Technical Assistance

What Health Care Facilities Need to Know About Legionella

After Legionella grows and multiplies in a building water system, that contaminated water then spreads in droplets small enough for people to breathe in. People can get Legionnaires’ disease when they breathe in small droplets of water in the air that contain the bacteria.

Less commonly, people can get Legionnaires' disease by aspiration of drinking water. This happens when water “goes down the wrong pipe,” into the trachea (windpipe) and lungs instead of the digestive tract. People at increased risk of aspiration include those with swallowing difficulties.

In general, people do not spread Legionnaires’ Disease and Pontiac Fever to other people. However, this may be possible in rare cases. 

Factors That Lead to Legionella Growth

A variety of internal and external factors can lead to a Legionella problem in your building, including:

  • Construction
  • Water main breaks
  • Changes in municipal water quality
  • Biofilm
  • Scale and sediment
  • Water temperature fluctuations
  • Fluctuations in pH
  • Inadequate levels of disinfectant
  • Changes in water pressure
  • Water stagnation

How to Address Legionella Growth

  • Ensure disinfectant amounts are correct
  • Maintain correct water temperatures
  • Prevent stagnation
  • Operate and maintain equipment
  • Monitor external factors

Learn more by visiting the CDC's page on Legionella or viewing a Legionella Fact Sheet (PDF).