eBook Key Takeaways: Legionella Monitoring & Prevention

//eBook Key Takeaways: Legionella Monitoring & Prevention

eBook Key Takeaways: Legionella Monitoring & Prevention

By |2019-11-15T10:00:40-05:00November 15th, 2019|News|0 Comments

This is the second in a series of posts highlighting key takeaways from our latest eBook, Best Practices: Water Management Programs For Facilities. Today we’re diving into Section 2, Legionella Monitoring & Prevention. Legionella is a bacterium that causes respiratory diseases, and factors such as pH, water pressure changes, biofilm, water stagnation, and more can influence Legionella growth in building plumbing systems.

Facilities can take steps to reduce the risk of Legionnaires’ disease – a Legionella water management program should identify areas or devices in the facility where Legionella might grow or spread, and take steps to reduce that risk.


ASHRAE 188 Legionellosis: Risk management for Building Water Systems is the most well known standard for Legionella management within facilities. 

The first step is to identify facilities that might encourage Legionella growth and expose vulnerable populations. The following facilities in particular should have a plan:

Healthcare facilities (especially those that house patients overnight or treat patients with acute medical problems/weakened immune systems)

  • Retirement facilities that house people over the age of 65
  • Building with centralized water heating system and multiple housing units (i.e. hotel or high-rise apartment complex)
  • Any building with more than 10 stories
  • Any facility with a cooling tower, hot tub, decorative fountain, mister, atomizer, air mister, or humidifier 

Next, a water management team should be formed – usually a multidisciplinary group of facility staff and public health experts, including a team member who is accredited as well as someone with infectious disease expertise. The team should create a monitoring plan by identifying the water path – including where water enters the facility, is distributed (hot or cold), and where waste water exists. 

Facility plumbing fixtures and devices should be added to a flow diagram to identify risk areas for Legionella growth. High risk areas might include:

  • High stagnation zones/fixtures/devices
  • Parts of facility serving high risk patients
  • Areas with low or no disinfection
  • Conditions for spread of bacteria
  • Conditions/areas with temperatures promoting growth 

Monitoring & Tracking

Once a plan has been developed, monitoring activities can include both Legionella sampling and risk or treatment parameter surveillance. The topic of monitoring frequency is still being debated

The standard method for Legionella lab analysis is a culture and there are a variety of field instruments and methods. Field staff should be educated on sample collection procedures for each location or device. 

Certain processes inside your facility such as heating, storing, and filtering may degrade the quality of your water as they use up disinfectants. Monitoring water parameters such as temperature, chlorine levels, and treatment may help you reduce Legionella risk.


It’s crucial to develop a clear communication plan with the program team and outside partners to stay aware of any activities that may alter water quality in the building and to increase responsiveness when Legionella is detected or when a case is diagnosed.

Some key aspects of a clear communication plan:

  • Facilities should maintain ongoing dialogue with water provider, stay aware of treatment or distribution maintenance activities that may impact water supply
  • Transparent communication with community is key, especially when diagnosed cases are discovered
  • All outreach should include where Legionella was found, what steps are being taken to reduce exposure, and how individuals can protect themselves 

To go more in-depth, download our full eBook here.

About the Author:

Kelly Smith

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