Legionella isn’t a new risk, but one too many teams still overlook.

Insight

4 minutes

16 June 2026

As the temperature goes up, so does the risk of legionella, a naturally occurring bacteria that can become a serious health risk.

Legionella can grow in commercial water systems that are not properly maintained, including plumbing systems, cooling towers, and decorative water features such as fountains. 

Legionella bacteria can cause Legionnaires’ disease, a severe and potentially fatal form of pneumonia. The bacteria can also lead to a less severe flu-like condition known as Pontiac fever. Infection typically occurs when people inhale contaminated aerosolized water droplets or mist from sources such as showers, hot tubs, or cooling systems.

Risk levels and related cases often increase during warmer months when higher water temperatures create ideal conditions for bacterial growth in these water systems. 

A growing risk: trends and recent outbreaks

According to the CDC, reported Legionella cases have increased steadily over the past two decades with an estimated 8,000 to 18,000 people hospitalized each year. This rise is linked to aging infrastructure, warmer temperatures, and more widespread testing. In 2025, New York City experienced one of the largest outbreaks in recent history, with over 114 confirmed cases, 90 hospitalizations, and seven fatalities. The source was traced to cooling towers across several city and privately owned buildings.

In the first half of 2026, multiple cases have been reported across the United States. The most recent occurring in Santa Clara, California, where at least 18 people were infected within a cluster of healthcare facilities.

These incidents highlight the importance of proactive risk management. Building owners, property managers, and HVAC professionals play a critical role in reducing exposure by implementing effective water treatment and maintenance programs. Consistent monitoring and system upkeep are essential to minimizing Legionella risk and protecting public health.

Strengthening compliance to avoid risks

BY following CDC guidance for building water monitoring and implementing proactive compliance strategies, organizations can mitigate risks, protect public health, and significantly reduce exposure:

  • Implement a comprehensive water management plan – Establish a formal water management plan aligned with industry standards (such as ASHRAE). This should include system mapping, risk identification, control measures, and clear accountability.
  • Conduct routine system cleaning and disinfection – Regular maintenance is critical. Ensure proper water temperatures, disinfectant levels, and system flow. Conduct routine inspections, cleaning, and testing to detect issues early.
  • Address stagnant water risks – Flush systems that are not in regular use, especially after building shutdowns or reduced occupancy. Stagnation creates ideal conditions for bacterial growth.
  • Test and document – Conduct periodic Legionella testing where appropriate and maintain detailed records of maintenance activities, results, and corrective actions. Documentation is key for both risk management and regulatory compliance.
  • Install and maintain an effective disinfection system – Use appropriate disinfection methods such as chlorination, secondary disinfection systems, or other approved treatments. Monitor performance regularly to ensure consistent and effective control of bacterial growth.

The Legionella liability gap in standard insurance programs

Legionella claims can result in substantial financial liability, with reported settlements and jury verdicts over $5.2 million. Bodily injury, legal defense, and cleanup costs are often excluded from standard commercial general liability (CGL) policies, a gap many property owners don’t realize. Dedicated environmental liability coverage can help address this exposure and close critical gaps.

Solutions built around your unique risk

Navigating Legionella regulations requires a clear understanding of federal, state, and local requirements, as well as industry standards. Compliance with these regulations is essential for preventing outbreaks and avoiding legal liabilities. Our team of experts focus on guiding our clients with a combined advisory and insurance approach. We help organizations interpret regulatory expectations, assess exposure within their water systems, and implement practical risk management strategies aligned with industry best practices.

From an insurance perspective, we evaluate how Legionella-related risks are addressed within your existing risk management programs, identify potential coverage gaps, and structure a solution that responds effectively in the event of a contamination incident or outbreak.

The goal is not only to support compliance, but to strengthen resilience. By aligning proactive risk management with the right insurance strategy, clients are better positioned to reduce the likelihood of incidents and manage the financial and reputational impact if they occur.

Contact us for more information on Legionella risk management

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    Jared Dubrowsky

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    Environmental