What Facility Managers Get Wrong About Legionella (and How to Fix It)

Legionella is one of the most misunderstood risks in building and healthcare facility management. Despite decades of research, countless outbreaks, and updated regulatory standards, many facility teams still rely on outdated beliefs or incomplete strategies that leave them—and their occupants—vulnerable.

Here are the top myths we encounter—and what you can do today to correct course.

Myth #1: “If I don’t have a cooling tower, I’m not at risk.”

The truth: Cooling towers are high-risk, but they’re far from the only concern. Domestic hot and cold water systems, decorative fountains, ice machines, humidifiers, spas, and even plumbing dead legs can harbor Legionella bacteria. In fact, the majority of outbreaks in healthcare facilities stem from potable water systems.

What to do: Take a whole-system view. Any water system that can aerosolize water or sit stagnant is a potential breeding ground.

Myth #2: “We test annually, so we’re covered.”

The truth:Testing is just one component of a compliant water management program—and it’s not even mandatory in many jurisdictions unless triggered by risk factors. A “pass” on a water test doesn’t mean your system is safe, and a “fail” doesn’t mean you're non-compliant unless you lack a documented response plan.

What to do: Shift your mindset from testing to ongoing risk management. Regular flushing, temperature monitoring, disinfectant residual tracking, and system inspections matter more than one test result. Legionella control is a process, not a checkbox.

Myth #3: “We only need to worry about Legionella in older buildings.”

The truth: While aging infrastructure can increase risk, newer buildings often have complex plumbing systems, oversized water heaters, and water-saving features that unintentionally promote stagnation—a perfect storm for Legionella growth.

What to do: No matter the age of your facility, design and use patterns matter. After any renovation or construction, update your Water Management Plan and test for Legionella during commissioning.

Myth #4: “We use chlorine, so we’re protected.”

The truth: Standard municipal disinfection can break down before it reaches every point in a building—especially in large, multi-story, or underused systems. Legionella can survive and even thrive in low-residual environments and inside biofilms.

What to do: Consider a secondary disinfection strategy. Products like Water Guard MO, our proprietary mineral oxychloride solution, offer long-lasting control inside piping systems—without the harshness of high-dose chemicals.

Fix the Myths Before They Cost You

Whether you're managing a hospital, senior care center, hotel, or commercial property, don’t let misconceptions put your people—or your compliance—at risk.

Legionella Specialties can help you review your water management program, identify weaknesses, and implement effective prevention strategies with minimal disruption to your operations.