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Turning off drinking fountains or disconnecting every other sink to make sure students are social distancing may allow water in the pipes to the disconnected fixtures to stagnate.

Growth of Legionnaire’s disease-causing bacterium is just one risk from stagnating water systems

As the world has dealt with the COVID-19 pandemic, many school buildings have sat idle for many months longer than usual. The return to these buildings is uncovering another potential health risk. In fact, COVID-19 lockdowns may have helped foster the growth of dangerous bacteria.

Earlier this year, studies raised concerns that stagnant water in the pipes and water systems of buildings vacated by the COVID-19 pandemic would lead to health risks. These concerns seem to have been justified.

Ohio officials recently announced that Legionella, the bacterium that causes deadly Legionnaire’s disease, or legionellosis, was found in five school water systems. Soon afterward, Pennsylvania officials announced the discovery of the microbe in four of their schools. Nine positive Legionella tests in a week are far more than expected under normal conditions, and the number of schools testing positive for Legionella has increased since the initial reports.

Spread of Legionella

Legionellosis is a type of pneumonia named for its first known outbreak among American Legion convention-goers in 1976. The air-conditioning system at the Philadelphia hotel hosting the convention was identified as the source of the bacterium, but Legionella is also known to grow in filters, heaters, tanks, pipes, and cooling towers.

The disease can be contracted when stagnant water containing Legionella is aerosolized and inhaled, for instance during showers, washing hands, and  toilet flushing, ironically some of the very activities encouraged to prevent the spread of COVID-19.

Fortunately, as with COVID-19, most children don’t appear to be at high risk, but older students, adults, and those with weakened immune systems may be more vulnerable. Children do run the risk of contracting a less dangerous disease, Pontiac fever, from Legionella, but the extent of the risk is unknown. To complicate matters, COVID-19 and Legionnaire’s disease share many symptoms, leading to risk of misdiagnosis.

Lockdowns and Legionella Growth

COVID-19 lockdowns since March have left many buildings vacant, which can lead to water stagnation in their pipes and water systems. It’s the perfect environment for Legionella and other bacteria. Most schools do not have water management plans, and, to make matters worse, some COVID-19 precautions may foster Legionella. Turning off drinking fountains or disconnecting every other sink to make sure students are social distancing may allow water in the pipes to the disconnected fixtures to stagnate and, therefore, become a vector for a disease worse than COVID-19. Some school buildings may contain as many as 300 water outlets.

Flushing Water Pipes

The U.S. Centers for Disease Control and Prevention has offered guidance on reopening buildings. Periodically flushing pipes at schools with chlorinated water generally is an effective way to stop bacteria formation, but chlorine levels in pipes can drop to zero in only 72 hours due to contact with organic and inorganic compounds in the water systems.

Protocols must be regularly observed and must include all fixtures; however, even one school that had been flushing regularly since July discovered Legionella in its pipes and was forced to shock its water system with a higher chlorine concentration. Legionella can even survive in the absence of water stagnation within biofilms that tend to form and adhere to the bottom of both hot and cold water pipes.

It is unclear to what extent Legionella contamination has really increased because of shutdowns. School buildings already typically remained closed during summer vacations, and a janitor in one of the Ohio schools tested may have died of Legionnaire’s disease in the year before the COVID-19 pandemic even made its way to America.

Testing at Ohio schools has been influenced by warnings of post-lockdown stagnant water issues involving not only bacteria, but also lead and copper buildups. So, the reports of Legionellosis there come with the caveat that the increased incidence may, to some unknown extent, be the result of more detection.

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