Keeping Your School Safe From Legionella

Keeping Your School Safe From Legionella

Students and faculty wash their hands, drink water and shower at school buildings. Measuring and maintaining water quality is a crucial job for schools and their building managers. Legionella bacteria are one of the potential contaminants found in schools’ water systems.

With many schools and universities planning to open their doors after months of remote learning during the COVID-19 pandemic, water quality questions are an essential consideration for administrators and building managers. How can schools understand the risk of Legionella and take steps to mitigate it?

Our Legionella Testing & Control Services

Possibility of Legionnaires’ Disease in Schools

Legionella bacteria naturally live in freshwater, but when they proliferate in a building’s water system, these bacteria can cause illness. Exposure to these bacteria can cause Legionnaires’ disease and Pontiac fever. Pontiac fever, the milder of the two illnesses, causes body aches and fever. Legionnaires’ disease is a more severe illness that infects the lungs. Symptoms of this disease include cough and shortness of breath, in addition to the body aches and fever typical of Pontiac fever. When Legionella bacteria contaminate a water system, people can become infected by breathing in water droplets.

Legionnaires’ disease spreads when people breathe in water droplets carrying Legionella bacteria. You do not get sick from drinking the water contaminated by these bacteria. People typically get the disease from contact with contaminated water, rather than getting it from another infected person.

The first reported outbreak of Legionnaires’ disease happened in 1976. Since then, health officials have tracked occurrences of the disease, though it is likely that cases still go unreported. The number of cases reported to the CDC has increased over the past two decades. There were a total of 10,000 cases of the disease in 2018 alone.

Risk Factors for Legionnaires' Disease

Risk Factors for Legionnaires’ Disease

Why might your school be in danger of a Legionnaires’ disease outbreak?

  • Lack of use: Stagnant water is a potential breeding ground for bacteria, including Legionella. With school closures due to COVID-19, water has been sitting in pipes for months. Multiple schools have discovered the presence of dangerous bacteria in their buildings’ plumbing systems. The Centers for Disease Control have released guidance on reopening safely after long periods of shutdown. Water systems that go long periods without use are at risk of Legionella, as well as mold and other potentially dangerous contaminants. The water can stagnate and promote the growth of contamination in biofilm and reduce the amount of disinfectant in the system.
  • Water systems: School buildings use water in multiple different ways. The building can have water fountains, showers, bathroom sinks, kitchen sinks and decorative foundations. All these different use sites represent the potential for infection via Legionella bacteria. Some water systems, such as cooling towers, have a documented risk of Legionella contamination if not properly maintained and cleaned. Some school buildings use cooling towers for their HVAC systems. These water systems contain large amounts of water, which might host an overgrowth of Legionella bacteria.
  • Water temperature: The conditions need to be ideal for Legionella to grow. Temperature is one of the essential environmental factors to consider when analyzing the risk of these bacteria. Legionella typically grows at temperatures ranging from 70 to 113 degrees Fahrenheit. The use of hot and cold water in plumbing systems can encourage the growth of these bacteria.
  • Infrequent maintenance: When schools fail to keep their water system correctly maintained, it can become the ideal environment for Legionella overgrowth. Upkeep, such as regular flushing, can help prevent biofilm buildup, where Legionella thrives. Regular maintenance also helps clear the system of debris and minimizes the risk of corrosion to the pipes.
  • No testing: Inconsistent guidelines govern the testing for Legionella at schools in the United States. In many cases, schools are under no obligation to perform regular testing for the bacteria. Despite varying regulations, Legionella can turn up in the water supplies of school buildings and cause infection. When this happens, the school will need to take corrective measures.

Who Is in Danger of Legionnaires' Disease?

Who Is in Danger of Legionnaires’ Disease?

Not everyone who gets exposed to Legionella will develop Legionnaires’ disease. Most healthy people are unlikely to become ill. Those who are most at risk of Legionnaires’ disease include the following.

  • People with compromised immune systems: Immunocompromised people are at higher risk for many different opportunistic infections, such as Legionnaires’ disease. Undergoing chemotherapy for cancer can weaken the immune system, as can other immunosuppressant drugs. Schools might have students and staff living with compromised immune systems every day.
  • People with other health conditions: Several health conditions can make a person more vulnerable to an infection like Legionnaires’ disease. People who have chronic lung disease, diabetes, cancer, kidney failure and liver failure are at higher risk of becoming infected with this disease.
  • Smokers: Legionnaires’ disease affects the lungs, as does smoking. People who currently smoke or have smoked in the past are at higher risk for this disease.
  • Older people: People over age 50 are at higher risk of infection with Legionella bacteria.

Testing Your School Water Supply

Testing for Legionella bacteria is largely voluntary, and rules can vary depending on the school system. However, testing can identify these dangerous bacteria and give facilities the time to address it before experiencing an outbreak.

Developing a water management program can help schools detect the presence of Legionella and other harmful bacteria. Armed with the test results, schools and their building managers can take measures to protect students and staff. Testing is a crucial first step in establishing a water management program. How does testing your school water supply work?

  • Understand the risk factors: Before scheduling a test and establishing a water management program, consider the risk factors. Has your school been unoccupied for a long time? Is the plumbing system old? Does the water system undergo regular maintenance, or has it been a while? Has there been an outbreak of Legionnaires’ disease in the area? Consider why testing is essential and what could happen if the school decides to forgo testing for the time being. Survey the school’s water system to understand the different risks. It is also vital to take a look at current practices. Have you regularly maintained your water system? Once a building manager understands the risks and current practices, they can present a compelling proposal for testing the school water supply.
  • Schedule environmental sampling: Environmental sampling is a vital part of mitigating risk as you develop a water management program. Schools and universities should find a trusted partner to help with the sampling process. This partner could be an ISO-certified business, like Chardon Laboratories, that helps manage the sampling process and any necessary remediation. An expert water treatment company will help schools determine how and where to conduct environmental sampling. A professional can take samples from several different points throughout the water system based on risk analysis. After a technician takes samples for testing, they’ll send them to a laboratory for testing.

How Often Should You Test Your School’s Water?

Determining how often to conduct testing will be a matter of a school’s specific risk profile and any potential regulatory requirements you must meet.

  • Determine water quality metrics: Quality metrics around Legionella and other potential water contaminants, like lead, are a crucial element of a water management program. What should you test, and what should the results look like? With established quality metrics, schools can begin implementing measures to regularly check those metrics and maintain them. If your water system fails to meet those quality metrics, the water management plan should have documented steps for disinfection and remediation.
  • Track your data: Having established a testing routine, schools will accumulate data around their water systems and water quality. Building managers can use that data to gain a clear-cut picture of how the system is functioning over time. Any changes in the data could indicate an issue to address. If another shutdown happens, whether due to regularly scheduled breaks or another major disruption like COVID-19, the building manager will have historical data to use as a benchmark for when the school plans to reopen for students and staff.

Many schools and universities have budgetary concerns to weigh when determining whether to test the water supply. Each school takes a unique approach to risk tolerance and mitigation, but testing can play a valuable role in keeping everyone who uses the water at the school safe.

Water Treatment for Legionella in Schools

Water Treatment for Legionella in Schools

Disease control is vital for schools and universities. Once your school has discovered a pathogen like Legionella in the water supply, you must address it. If your school’s test results come back positive for Legionella, it is best to work with an expert in water treatment to form an action plan for mitigation and prevention of further overgrowth of the bacteria in the future. Remember, schools in some locations may need to take specific steps following a confirmed Legionnaires’ disease outbreak.

Water treatment approaches for Legionella include the following.


Flushing a water system is a simple measure that can prevent Legionella overgrowth. It can also play a role in removing any detected bacteria from the system. Flushing a water system involves turning on every point of use in a school’s water system. You should run every faucet, shower, water fountain, eyewash station, etc., to flush any stagnant water from the system. Building managers and their teams should let the water run at its maximum temperature. The Centers for Disease Control recommend allowing the water to reach 120 degrees Fahrenheit or above, carefully following anti-scalding measures.

The team members responsible for overseeing the flushing process must take steps to protect themselves against splashing and aerosols. If the water system gets contaminated with Legionella, it could infect the staff members via aerosols released during the flushing process. Note that a single flushing is unlikely to clear a system contaminated with Legionella overgrowth.

System Cleaning

Flushing is an effective measure to help clear a water system, but some parts may need additional disinfection measures. For example, cooling towers, ice machines, fountains and hot tubs will likely need further disinfection to prevent Legionella contamination or manage an outbreak.

Chemical Treatment

Legionella contamination in a school’s water supply may require chemical treatment. A Legionella disinfection strategy may use chemicals such as chlorine, chlorine dioxide, chloramine and ozone. These chemicals inactivate the bacteria in the water, making sure these organisms cannot infect people. They can be effective even if biofilms protect the bacteria in question. The chemical treatment’s efficacy is not always 100%, and it will depend on factors like water temperature and pH levels.

Other Options

Copper-silver ionization systems and ultraviolet light are two other approaches to disinfecting water systems. Both these approaches inactivate various pathogens commonly found in water systems.

Following Legionella treatment, complete another round of testing to confirm that bacterial overgrowth in the water system is no longer a problem. Going forward, it will be vital to continue following a vetted and established water management plan.

Regular maintenance, including flushing and testing, can help prevent future outbreaks. Some water systems’ designs will make them more prone to contamination, a factor that will go into determining how often procedures like flushing and testing are necessary. Remember, it is also possible for Legionella to go undetected if it’s living in a biofilm, lurking until it grows to high enough levels to cause an outbreak. A carefully crafted water management plan can account for and mitigate this risk.

Chardon Labs Legionella Testing Services for Schools

Chardon Labs Legionella Testing Services for Schools

Chardon Labs provides comprehensive services to help schools assess and improve their water quality. Our team can perform a survey of your building’s water systems to detect the presence of Legionella and determine the level of risk. Next, we work with you to build and validate a water management plan to control the bacteria.

You want the peace of mind that comes with knowing students, teachers and staff can safely use the building’s water supply when school is back in session. We are here to help you make sure that is the case. Contact us to discuss Legionella testing and water management for your school.

Portrait of Matt Welsh, the co-president
Matt Welsh
Vice President, Water Consultant at Chardon Labs | Website | + posts

Matt Welsh is the Vice President and Water Consultant at Chardon Labs.  He helps consult a wide range of customers utilizing various methods of water treatment, from chemical to chemical-free approaches, large and small applications, and across a wide range of geographical influences.  With 20 years of water treatment experience, including a wide range of troubleshooting and service in potable water and non-potable HVAC and industrial applications, he is an expert in water treatment chemistry for cooling towers, boilers, and closed-loop systems.


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