Cooling Towers Testing and Treatment

Information and results for testing of Legionella bacteria in HVAC cooling towers

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Testing for the Legionella Bacteria

Out of an abundance of caution, HCPSS began proactively testing for the Legionella bacteria in September 2019. The school system tested samples from higher risk sites, namely all HVAC cooling towers across the school system. Testing was not conducted in response to any health concerns, or done to fulfill a requirement or request. This sampling is not required by federal, state or local regulations. The primary goal of the testing is to document cooling tower maintenance activities. Testing also provides benefits to Indoor Environmental Quality, however the risk of school staff/students contracting legionnaires disease is low due to the locations of the cooling towers and because “most healthy people exposed don’t get sick” (About Legionnaires' Disease | Legionella | CDC). It is not uncommon to find various Legionella species in cooling towers. According to the Occupational Safety and Health Administration, there are at least 50 Legionella species, 20 of which cause human diseases; however, the presence of the organism does not necessarily equate to risk of infection.

Frequently Asked Questions

Why isn’t testing being done at every school and facility?

Testing is done in HVAC cooling towers, which are only in place at 23 buildings. The list of locations can be found online.

If Legionella bacteria was found in my school’s cooling tower, is it safe to drink the water at school? Is it safe to wash my hands?

In testing, HCPSS collects samples from cooling towers, which are present only at the 23 buildings listed online and used to cool water as part of the building’s HVAC system. The school/office's drinking water or water used for other purposes does not come from the cooling towers.

If a test comes back positive, how is HCPSS getting rid of the Legionella bacteria?

If any Legionella bacteria is detected, remediation is performed, which includes chemical treatment and maintenance, such as super chlorination. After the remediation, another water sampling will be conducted to determine the effectiveness of the remediation. If the results continue to detect Legionella in the cooling tower, we will investigate and perform additional remediation until the testing comes back negative.

How were students, families and staff notified about this issue, and any applicable test results?

Information regarding Legionella testing was posted to the HCPSS website. An email was sent to staff and another to families. A separate email was sent to families at schools where cooling towers were found to have elevated levels.

HCPSS Contacts

  • Christopher Madden, Industrial Hygienist/IEQ Manager, Office of the Environment
  • Larsen Angel, Mechanical Engineering Manager, Department of School Facilities