Water System Maintenance Needed to Prevent Legionnaires' Disease Outbreaks

More effective water management might have prevented most of the Legionnaires’ disease outbreaks the CDC investigated from 2000 through 2014, according to the June 7, 2016 CDC Vital Signs report. Problems identified in these building-associated outbreaks included inadequate disinfectant levels, human error, and equipment breakdowns that led to growth of Legionella bacteria in water systems. The CDC released a new toolkit to help building owner and managers prevent these problems.


Legionnaires’ disease is on the rise. The CDC investigated the first outbreak of Legionnaires’ disease, a serious lung infection (pneumonia), in 1976. In the last year, about 5,000 people were diagnosed with Legionnaires’ disease and more than 20 outbreaks were reported to the CDC. People can get Legionnaires’ disease by breathing in small droplets of water contaminated with Legionella. Most people who get sick need hospital care, a course of antibiotics, and make a full recovery— but about one in ten people will die from the infection.


“Many of the Legionnaire’s disease outbreaks in the United States over the past 15 years could have been prevented,” said CDC Director Tom Frieden, M.D. M.P.H. "Better water system management is the best way to reduce illness and save lives, and today's report promotes tools to make that happen."


The Vital Signs report examined 27 building-associated Legionnaires’ disease outbreaks investigated by the CDC across 24 states and territories, Mexico, and Canada. For each outbreak, CDC researchers recorded the location, source of exposure, and deficiencies in environmental control of Legionella. Most identified outbreaks are in buildings with large water systems, such as hotels, long-term care facilities, and hospitals. Cruise ships are another place where Legionnaires’ disease outbreaks can happen. Legionella grows best in building water systems that are not well maintained.


The most common source of building-associated Legionnaires’ disease outbreaks was drinkable water (56 percent), including water used for showering, followed by cooling towers (22 percent), and hot tubs (7 percent). Other sources included industrial equipment (4 percent) and a decorative fountain/water feature (4 percent). In two outbreaks, the source was never identified.


Twenty-three of the investigations included descriptions of failures that contributed to the outbreak. In nearly half, more than one type of failure was identified.


  • About 2 in 3 (65 percent) were due to process failures, such as not having a Legionella water management program.


  • About 1 in 2 (52 percent) were due to human error, such as a hot tub filter not being cleaned or replaced as recommended by the manufacturer.


  • About 1 in 3 (35 percent) were due to equipment, such as a disinfection system, not working.


  • About 1 in 3 (35 percent) were due to changes in water quality from reasons external to the building itself, like nearby construction.


The CDC has released a new toolkit for building owners and managers: Developing a Water Management Program to Reduce Legionella Growth & Spread in Buildings: A Practical Guide to Implementing Industry Standards. Based on ASHRAE Standard 188, a document for building engineers, the toolkit provides a checklist to help identify if a water management program is needed, examples to help identify where Legionella could grow and spread in a building, and ways to reduce the risk of Legionella contamination.


The toolkit includes:


  • A simple yes/no worksheet to determine if an entire building or parts of it are at increased risk for growing and spreading Legionella,
  • A basic walkthrough of the elements of a Legionella water management program,
  • Scenarios describing common water quality problems and examples of how to respond to them to reduce the risk for Legionella, and
  • Special sections and considerations for those who work in healthcare facilities.


Most healthy people do not get Legionnaires’ disease after being exposed to Legionella. People at increased risk of Legionnaire’s disease are 50 years of age or older and have certain risk factors, such as being a current or former smoker, having a chronic lung disease, or having a weakened immune system. Signs and symptoms of Legionnaires’ disease can include cough, muscle aches, high fever, shortness of breath, and headache. Doctors use chest x-rays or physical exams to check for pneumonia. The doctor may also order tests on a patient sample of urine and sputum (phlegm) to determine if a lung infection is caused by Legionella.


“Years of outbreak response have taught us where to find Legionella hot spots,” said Nancy Messonnier, M.D., director of the CDC’s National Center for Immunization and Respiratory Diseases. “The toolkit will help building owners and managers better understand where those hot spots are and put measures in place to reduce the risk of Legionnaires’ disease.”


See the CDC Announcement


Also see the CDC’s Vital Signs report:


Also see the CDC's Toolkit on Developing a Water Management Program to Reduce Legionella Growth and Spread in Buildings


Also see the CDC's Legionella Clearinghouse


See also Medical Law Perspectives, June 2016 Report: How Risky Is Going to the Hospital? The Dangers and Liabilities of Healthcare-Associated Infections


See also Medical Law Perspectives, December 2015 Report: Pneumonia Complications, Hospitalizations, Deaths: Risks and Liabilities