Legionella Risks in Buildings After COVID-19 Closures

The COVID-19 pandemic forced buildings and campuses to close across the country. Proactive building managers used this time to schedule inspections, testing, preventive maintenance, and cleaning of HVAC and other systems. Many facilities, however, sat empty during this time. While building closures are an essential part of limiting the spread of the coronavirus, other health risks were elevated during this time. Including Legionella risks in buildings. This bacteria causes another type of lung infection, Legionnaires’ disease.

Reopening Plans

Like COVID-19, Legionnaires’ disease is an assault on the respiratory system. While not as severe as the condition caused by the coronavirus, Legionnaires’ disease is a form of atypical pneumonia resulting in symptoms of fever, coughing, shortness of breath, aching muscles, and headaches. In severe cases, vomiting and diarrhea may result. Unlike COVID-19, Legionnaires’ disease does not spread through human contact, but through drinking and inhaling infected water and water vapor.

As building managers plan to reopen in the coming weeks, caution is essential to any reopening strategy. The sharp decline in water use during closures results in a lack of chlorinated water in pipes. This contributes to conditions where Legionella bacteria can grow and spread. Legionella risks in buildings closed by coronavirus must be addressed before occupants return.

Going forward facilities managers need to be aware of the Legionella risks in their buildings. It should get included in plans for the design, construction, and expansion of water and air distribution systems as well as in their operations and maintenance. This reduces the risk for the spread of disease, improves indoor air quality, and creates a safer environment for building occupants.

Legionella Risks in Buildings

Legionella Water Management Plan. Covid-19

Make a plan.

Legionnaires’ disease is contracted after exposure to water that contains the Legionella bacteria. Hotel hot tubs and water fountains in schools and fitness centers and sprinkler systems in office buildings are at risk. Mist from cooling towers can also spread the bacteria in tiny water droplets that get breathed into the lungs.

Commercial buildings that have been closed for weeks or even months need a plan for reopening to reduce Legionella risks in buildings. This should include flushing out water lines and sanitizing them. Building managers plan for all types of contingencies, but low occupancy has not been a consideration for many. Changes to this way of thinking have already begun and the time to develop new plans is now.

Waterborne Disease

Earlier this year, Reuters reported that a group of Chinese doctors found that 20 percent of coronavirus patients also had Legionnaires disease. Also cited in the Reuters’ piece was the findings of a group of Japanese doctors, published in the International Society of Travel Medicine. These doctors wrote about their experience with a patient who was infected with both the coronavirus and Legionella bacteria. The Chinese research has not been peer-reviewed and the Japanese patient may be an outlier, but the Legionella risks in buildings that have sat empty is real.


Larger facilities should have a plan for dealing with the threat of waterborne illness. Small businesses, such as gyms, hotels, and restaurants, are more likely to be unprepared and must address issues of stagnant water before reopening. The risks for larger corporations, universities, and healthcare facilities are also high.

What Can Be Done?

Testing is needed to identify and eliminate Legionella risks in buildings. Pure Air Control Services’ Environmental Diagnostics Laboratory uses three methods to analyze water samples. The lab is a part of the CDC Elite Program and is also certified by the New York State Department of Health ELAP #12086 for Legionella Testing.


Our Building Sciences Services provide effective ways to minimize the development and spread of the Legionella bacteria. We evaluate indoor environments based on a number of parameters, including HVAC zones within a building. Our HVAC Hygiene Assessment gauges the impact that HVAC systems have on indoor air quality.


Contact Pure Air Control Services with questions about these services and Covid-19 or to schedule a complete Building Health Check. Call 1-800-422-7873 today or email us here.