How Building Water Systems Can Impact Health: Understanding Legionella Risks

The U.S. Environmental Protection Agency (EPA) recently launched a new educational resource titled Legionella in the Indoor Environment, highlighting the growing importance of managing these waterborne bacteria in buildings. Legionella occurs naturally in lakes, streams, ponds, and other freshwater environments, as well as in some soils. However, it can also colonize man-made water systems, including building plumbing and water distribution systems.

Health risks arise when Legionella disease bacteria (LDB) multiply and spread within a building’s water system, such as in pipes and water-using devices. Showerheads, sink faucets, humidifiers, and similar equipment can generate mist or fine water droplets that may carry the bacteria into the air. Infection can occur when individuals inhale these contaminated droplets.

Exposure to aerosolized water droplets containing LDB can lead to Legionnaires’ disease, a severe and potentially fatal form of pneumonia, or Pontiac fever, a milder flu-like illness. Common symptoms may include:

• Cough
• Fever
• Headaches
• Muscle aches
• Shortness of breath

“The water supply to your home and office is not sterile. It is expected to contain low concentrations of LDB and other microorganisms. So, the paradigm shift for facilities must be to manage water quality in order to minimize colonization of LDB water systems,” said Derrick A. Denis, Senior Vice President of Clark Seif Clark, Inc. “Our vulnerable populations with comorbidities such as age, illness, or unhealthy habits like smoking are more susceptible to contracting legionellosis. The vulnerable are also more prone to succumb to this disease, with a 40% mortality rate in healthcare settings. The good news from the CDC is 90% of Legionnaires Disease cases are preventable with well-planned and consistently executed water management. At CSC we help clients create viable water management plans to reduce the frequency of disease. And in the unfortunate event of an outbreak, we help clients navigate prudent response actions.”

To help businesses and organizations identify and reduce Legionella exposure risks, CSC’s industrial hygiene, infection control, and environmental professionals provide comprehensive water management programs, including Legionella testing, monitoring, consulting, and training services. In addition, Clark Seif Clark recently sponsored an educational video highlighting key EPA guidance on Legionella in the indoor environment, available at: https://youtu.be/I900sIkU1Ig

To learn more about this or other environmental, health, and safety services, please visit www.csceng.com, email csc@csceng.com, or call 800-807-1118.

About Clark Seif Clark, Inc. (CSC)
2026 marks CSC’s 30th year of helping clients in both the public and private sectors address indoor air quality, occupational health, and environmental, health, and safety (EH&S) issues. CSC is a leading provider of these services with multiple offices along the western seaboard and southwest. The company believes in science-based protocols and has a strong background in engineering, making them the preferred environmental consultants to industrial clients, healthcare facilities, architects, schools, builders, contractors, developers, and real estate professionals.

Contact Information

Paul Cochrane

President

Cochrane & Associates, LLC

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