By Kelly A. Reynolds, MSPH, PhD

Increasing rates of largely preventable Legionella outbreaks have prompted new standards and guidelines on reducing risks through education and training. A new and free, online training program is available to anyone and is expected to aid the development of effective water management programs to reduce Legionnaires’ disease.

Legionella hazards and outbreaks
Legionella is a water-based bacterial pathogen, meaning the organism is naturally and commonly found in water. At low levels, Legionella is typically not a risk but concentrations in water rapidly increase under conditions of stagnation, low chlorine residuals and optimal growth temperatures. The bacterium is spread via inhalation of aerosols. Outbreaks have been linked to cooling towers, showerheads, ice machines, hot tubs and decorative fountains. There are many sources for aerosolization of Legionella, including medical devices, humidifiers, faucets, showers, misters, atomizers and more. Any devices along the water distribution chain in building premise-plumbing can contribute to Legionella growth and transmission, including water filters, heaters and storage tanks.

Two primary diseases are caused by infection with the bacterium Legionella. One is Legionnaires’ disease (LD), a dangerous type of pneumonia. Symptoms of infection include a cough, shortness of breath, muscle aches, headache and fever. The second is Pontiac fever, a milder respiratory infection that mimics flu-like symptoms. People over the age of 50, smokers and those with other chronic illness (i.e., lung diseases) or who are immunocompromised are most at risk for infection and serious adverse health outcomes.

One out of 10 people who get Legionnaires’ disease will die from the infection and the incidence rate has increased four-fold from 2000-2014. While some of this may be due to better reporting, at least 20 outbreaks are reported every year in the US, resulting in around 5,000 cases. Most outbreaks are documented in buildings with large water systems, such as hotels, hospitals and long-term care facilities. The CDC estimates that nine out of 10 outbreaks could have been prevented if a proper water management program was in place.

Risk management
The Centers for Medicare and Medicaid Services (CMS) issued a memorandum to State Survey Agency Directors (on June 2, 2017), requiring healthcare facilities (including hospitals, critical-access hospitals and long-term care) to reduce Legionella risk in their building water systems.1 The requirement (42 CFR § 482) published in the Federal Register specifically states: “The hospital must provide a sanitary environment to avoid sources and transmission of infections and communicable diseases. There must be an active program for the prevention, control and investigation of infections and communicable diseases.” For critical access sites, (42 CFR §485.635) policies must include: “A system for identifying, reporting, investigating and controlling infections and communicable diseases of patients and personnel.” Finally for skilled nursing and nursing facilities, (42 CFR §483.80): “The facility must establish and maintain an infection prevention and control program designed to provide a safe, sanitary and comfortable environment and to help prevent the development and transmission of communicable diseases and infections.”

While these guidance statements may seem vague, there are clear recommendations publically available from the US Centers for Disease Control and Prevention (CDC) and the American Society of Heating, Refrigerating and Air Conditioning Engineers (ASHRAE). ASHRAE published an industry standard, accredited by the American National Standards Institute (ANSI), ANSI/ASHRAE 199-2018, Legionellosis: Risk Management for Building Water Systems as a guide to help minimize water-based pathogen disease by establishing minimum risk-management requirements for building water systems.2

Other useful resources include the CDC’s Toolkit: Developing a Water Management Program to Reduce Legionella Growth and Spread in Buildings: A Practical Guide to Implementing Industry Standards.3 In the toolkit, is a one-page, yes/no worksheet to determine if a building or specific devices need a water management program. A ‘yes’ answer to any of the eight assessment questions prompts the user to take action, starting with free training on how to create a water management program.

Training basics
Most recently, the University of Arizona Zuckerman College of Public Health, in collaboration with the Western Region Training Center, CDC, National Network of Public Health Institutes and an advisory team from industry, health departments and other national and federal stakeholder organizations launched a free, online training program. The training, Preventing Legionnaires’ Disease (PreventLD Training) is a step-by-step guide to putting together a water management program team and designing a site-specific water management program.4

PreventLD Training is divided into four modules and two case studies. Module A: Getting Started, provides an introduction to Legionella and Step 1: Creating a water management program team. Module B: Hazard Analysis, includes Step 2: Describe the building water systems using text and flow diagrams and Step 3: Identify areas where Legionella could grow and spread.

Module C: Hazard Control, walks users through Step 4: Decide where control measures should be applied and how to monitor them, along with Step 5: Establish ways to intervene when control limits are not met. Finally, Module D: Confirmation, houses Step 6: Make sure the program is running as designed and is effective (verification and validation) and Step 7: Document and communicate all the activities of your water management program.

The case studies are real-world examples, applying the training steps to: 1) a manufacturing facility and 2) a skilled nursing facility. Optional training materials include templates to create an action plan for developing a water management team and program. Available for download are guides for assembling your water management program team, hazard analysis and control tables, potable and non-potable source-water flow diagrams and risk-characterization worksheets.

Access to the training is available at the Western Region Public Health Training Center at the University of Arizona or by following a link on the CDC website: While the training is formatted as a narrated video, closed captioning and written transcripts of the narrative are also available in Supplemental Materials. Average user time is approximately 30 minutes per module for a total time of three hours. Users can start and stop the training at any time, returning later to complete a module. Individuals who complete the course are eligible to receive continuing education units (CEUs) through the National Environmental Health Association (NEHA).

The benefit of the PreventLD Training is that it outlines how facilities can reduce the risk of Legionella via a step-by-step approach through the use of water management teams and programs. The training is well aligned with ASHRAE 188 and covers a range of high-risk building water systems, including potable water, cooling towers, hot tubs and decorative water features. Being able to offer the training for free and online is a bonus for users who can even earn continuing education units from the National Environmental Health Association (NEHA). Inclusion of case studies and templates provides practical resources for users to immediately plan an individualized approach to Legionella prevention, tailoring those resources to their own site-specific conditions.

The training was developed with a range of professionals in mind. For anyone involved in facility water maintenance, the training is essential and even mandated for healthcare facilities. This may include public health professionals, infection preventionists, building managers, maintenance/engineering staff and safety officers. Anyone in the field of water purification, conditioning and processing can also benefit from these resources. This would include equipment and water treatment suppliers as well as consultants. While the training is geared toward large-facility water systems, understanding individual and population risks, along with environmental conditions of increasing hazards and controls is important for homeowners and smaller system managers as well.


  1. CMS. Requirement to Reduce Legionella Risk in Healthcare Facility Water Systems to Prevent Cases and Outbreaks of Legionnaires’ Disease (LD). (2017). Available at: (Accessed: 19th April 2019).
  2. ASHRAE. ANSI/ASHRAE Standard 188-2018, Legionellosis: Risk Management for Building Water Systems. (2018). Available at: (Accessed: 19th April 2019).
  3. CDC. Developing a Water Management Program to Reduce Legionella Growth & Spread in Buildings A PRACTICAL GUIDE TO IMPLEMENTING INDUSTRY STANDARDS. (2017).
  4. CDC, UAMEZCOPH, WWPHTC, N. Preventing Legionnaires’ Disease (PreventLD Training). (2018). Available at: (Accessed: 19th April 2019).

About the author
Dr. Kelly A. Reynolds is a University of Arizona Professor at the College of Public Health; Chair of Community, Environment and Policy; Program Director of Environmental Health Sciences and Director of Environment, Exposure Science and Risk Assessment Center (ESRAC). She holds a Master of Science Degree in public health (MSPH) from the University of South Florida and a doctorate in microbiology from the University of Arizona. Reynolds is WC&P’s Public Health Editor and a former member of the Technical Review Committee. She can be reached via email at [email protected]


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