School districts discover Legionella as stagnant water systems recommissioned


Students may be returning to school this fall in some areas of North America armed with not only masks to protect against COVID-19, but bottled water, too, as officials begin to discover harmful bacteria in pipes left unused for some six months.

Legionella pneumophila bacteria, in particular, can cause severe pneumonia or lung infection. Although it exists naturally in freshwater environments like lakes and streams, it can also grow within dormant buildings’ water systems such as those locked down during the pandemic.

Additionally, water pipes left unused for long periods of time also elevate risks of mycobacteria, pseudomonas aeruginosa, and acanthamoeba.

In Pennsylvania, several schools have already discovered Legionella, including four schools in the Fox Chapel School Districts, and a junior high school in the Plum School District.

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In Ohio, too, Legionella bacteria has been found in several schools, particularly in the Vandalia-Butler district, board officials say.

The water, which can become stagnant within the pipes, equipment, and any storage tanks, will be heated to 160 degrees Fahrenheit, then drained through all outlets, faucets and spigots, refilled and then flushed again.

No individuals have reported any exposure within any of the schools at this time, but Legionnaires’ disease has sickened and killed more people in the U.S. than any other reportable waterborne disease.

In Canada, however, at least two people remain in a British Columbia hospital following suspected exposure to Legionella pneumophila bacteria in central New Westminster in recent weeks. It remains unclear where the exposure occurred specifically, however, a team of investigators is engaged in an environmental assessment to determine which buildings have cooling towers, air conditioning units and decorative water features, all of which carry risk of the bacteria.

People can also get Legionnaires’ disease when they breathe in small droplets of water in the air that contain the bacteria. The risk of death for people who develop legionnaires’ disease pneumonia ranges between 10 to 25 per cent, according to Fraser Health.

In May, the Canadian Water and Wastewater Association released a set of reopening guidelines for building owners. Notably, flushing and disinfecting systems are key components of recommissioning. Pipe material and overall system integrity, such as pressurization issues, should also be considered.

An ongoing U.S. study funded by the National Science Foundation’s Rapid Response Research program is examining bacterial changes during extended building closures, and then developing evidence-based plumbing remediation methods to address water quality deterioration. The team is collecting samples at sinks and water fountains in three buildings – tracking temperature, oxygen, heavy metals such as lead and copper, and how microbial communities in pipes change over time.


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