The CDC has issued guidelines for reopening businesses and buildings after coronavirus lockdowns. A spokeswoman for the agency said its guidelines are “applicable to all types of buildings,” including schools. But the vagueness of many of the guidelines, according to Dr Whelton, means that schools can do as much or as little general preventative measures and claim to comply.
The usual way to guard against the growth of Legionella is a process called flushing. Bringing fresh water into the system maintains a small dose of chlorine in the system, which limits the ability of bacteria to spread. But rinsing must be done regularly and for all outlets. It means running every faucet, shower and toilet.
One of the Ohio schools that found the bacteria, Englewood Elementary in the Northmont City School District outside of Dayton, began flushing its system in July. When a water management company discovered Legionella last week, it shut off all the water in the building and sent a high level of chlorine into the system. A district spokeswoman said they were continuing to test the water to ensure its safety.
The only way to know if the rinse is effective is to test the water. A single rinse will not eliminate legionella if it is present. Milton Union High School in Ohio began testing its water in late July. They found that after 72 hours the chlorine level had dropped to zero. They flushed again and when they tested 24 hours later it was back to zero. They tested the water and found Legionella.
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Updated on August 27, 2020
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Caitlin Proctor, a postdoctoral fellow at Purdue who studied legionella during the lockdown, said that despite the use of chlorine, the bacteria’s biofilms can prevent some of them from disappearing completely. “They can proliferate again once the disinfectant wears off.”
Officials with the Fox Chapel Area school district in a suburb of Pittsburgh, which also detected the bacteria in several schools, said in an email to parents that they were sending high temperature water through the system. This process, known as heat shock, has been suggested by county health officials as another way to kill bacteria. However, some industry groups are questioning the effectiveness of heat shock in stopping Legionella.
Some schools do not have the budget to test for Legionella and other waterborne hazards. But even schools that do face a lack of authoritative advice. Many, for example, test their water directly after rinsing. Because the water is cool, Legionella will not appear, making the test ineffective.