Post-Pandemic Re-Opening: Managing Legionella Bacteria in Your Building Water Systems

By Hilary Nardone, Environmental Group Training Manager
Certified ASSE 12080 Legionella Water Safety and Management Specialist

As the United States prepares to live in a post-pandemic world, many office buildings and hotels that have seen low occupancy over the past year are taking steps to re-open at full capacity. Ensuring that these buildings are safe for occupants is a top priority as people resume working at an office and begin to travel again. Minimizing your facility’s risk for Legionella bacteria amplification is a crucial step in prioritizing the health and safety of building occupants. Here are some effective tools to do so.

For buildings that have been closed or seen low occupancy, stagnant water in the building’s piping systems poses a severe risk for Legionella bacteria amplification. Stagnant water allows for a drop in disinfectant levels and an increase in biofilm accumulation, both of which are factors that contribute to the amplification of Legionella bacteria and other opportunistic waterborne pathogens. The American Water Works Association (AWWA) and the International Association of Plumbing and Mechanical Offices (IAPMO) recently developed a guide to help building managers address water stagnation in their plumbing systems. The guide, ‘Responding to Water Stagnation in Buildings with Reduced or No Water Use’ outlines different strategies to combat water stagnation. [1] While the guide considers the variability of each building’s water piping system, below are two critical takeaways to consider before your facility re-opens:

  1. Establish a flushing procedure at your facility.
    Deciding on how many outlets to flush and if points of entry and other mechanical devices should be considered, as well as the frequency of flushing, can depend on several factors including the size and complexity of your building.
  2. Consider routine environmental sampling for Legionella bacteria to validate your flushing protocol’s effectiveness. Check out our recent blog post on the CDC’s new recommendations for routine environmental Legionella bacteria sampling.

Implementing a flushing protocol at your facility is just one way to minimize Legionella bacteria amplification and to help ensure a safe environment after months of low occupancy. Developing a chlorine map of your facility can detect areas where there are insufficient disinfectant levels to minimize Legionella bacteria growth, pinpointing areas where increased flushing or supplemental disinfection will further mitigate risk.

Finally, developing a comprehensive and site-specific Water Management Program (WMP) that complies with ASHRAE Standard 188-2018 will consider all Legionella control locations including but not limited to: cooling towers, decorative fountains, domestic water tanks, hot tubs and spas, faucets, and showers. WMPs should be considered for all building offices and hotels. In fact, the CDC has stated that Legionella bacteria can grow and spread in many areas of hotels and resorts, stressing the need that WMPs can help protect hotel workers and patrons, especially as hotels resume operating at full capacity. [2]

Barclay Water Management, Inc. can work with your facility to develop and implement a Water Management Program, create chlorine maps, and conduct routine environmental Legionella bacteria sampling, all of which address building water stagnation and other Legionella bacteria control locations and are crucial steps in prioritizing health and safety as office buildings and hotels re-open and resume operating at full capacity.

[1] AWWA/IAPMO. Responding to water stagnation in buildings with reduced or no water use. Published October 2020. Accessed June 10, 2021.

[2] CDC. Legionnaires’ disease prevention: making a splash with safe water. Updated March 25, 2021. Accessed June 11, 2021.

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