By Brian Nemetz, CMC, National Technical Director of Industrial Hygiene, at Partner
Legionella bacteria have long been a concern for building owners and operators, particularly after high-profile outbreaks in major cities. In recent years, regulations governing Legionella management are expanding rapidly across the United States, and in some cases, becoming more stringent at the local level. For commercial real estate owners and managers, staying informed is an essential part of risk management and operational compliance.
What is Legionella?
Legionella is a naturally occurring bacterium found in water that can grow in building water systems such as cooling towers, plumbing systems, fountains, and hot water tanks. When contaminated water becomes aerosolized, people can inhale it and develop Legionnaires’ disease, a serious form of pneumonia. Outbreaks are often tied to complex building systems where water stagnation, temperature, and maintenance conditions allow bacteria to thrive. As building systems age and occupancy patterns shift, particularly after periods of low use, these risks can increase.
Historically, Legionella guidance at the federal level has been largely advisory. Organizations such as the Centers for Disease Control and Prevention and OSHA provide recommendations, while ASHRAE Standard 188 has become a widely accepted framework for water management programs. However, enforceable requirements have typically been set by state and local jurisdictions, and that is where the landscape is evolving most quickly.
State and Local Regulations Increasing
New York has been at the forefront of Legionella regulation since a series of outbreaks in 2015 prompted statewide action. New York State implemented requirements focused primarily on cooling towers, including registration, routine inspection, and testing. More recently, New York City has taken an additional step by introducing regulations that go beyond state rules. These updated requirements place greater emphasis on routine monitoring, documentation, and operational controls for cooling towers, signaling a shift toward more rigorous oversight at the local level.
This layering of requirements is an important development for property owners. It highlights that compliance is no longer just a state issue. Local jurisdictions may impose their own rules that are more detailed or more demanding than broader state regulations. Owners with multi-state portfolios may therefore face a patchwork of obligations that vary by city, building type, and system complexity.
Beyond New York, other states are also moving in this direction, although not always in the same way. Below is the basic information for the newer regulations:
- Michigan – Based upon ASHRAE Standard 188-2018
- Ohio – Specific hospital requirements
- Virginia – Specific public-school regulations
- Illinois – Specific health care regulations
- New Jersey – Based upon ASHRAE Standard 188-2018
- Pennsylvania – Regulations are in progress.
- Several other states are reportedly in the process of establishing regulations.
Legionella Risk Management for Building Owners
This trend suggests that Legionella regulation will continue to evolve. Rather than a single nationwide standard, the United States is seeing a gradual expansion of targeted requirements driven by local concerns and past incidents. For property owners and managers, this creates two key challenges.
The first is awareness. Regulations can change quickly, and requirements may differ significantly even between neighboring jurisdictions. A building that is compliant today may need additional documentation, monitoring, or system upgrades tomorrow.
The second is implementation. Many regulations require more than simple testing. They often call for comprehensive water management programs that include system assessments, routine monitoring, corrective actions, and detailed recordkeeping. These programs must be tailored to each property’s specific water systems, which can vary widely depending on age, design, and usage.
The good news is that most buildings already have many of the components needed to manage Legionella risk effectively. These include regular maintenance practices, mechanical system oversight, and environmental, health, and safety protocols. Regulatory compliance is usually a matter of aligning these existing practices with evolving regulatory expectations and documenting them in a way that satisfies inspectors and public health authorities.
This is where experienced EHS (Environmental, Health and Safety) consultants can provide significant value. They can help interpret regulatory requirements, develop or refine water management programs, and conduct risk assessments that identify potential problem areas such as stagnant water lines or underutilized fixtures. They can also assist with sampling strategies, training, and ongoing compliance support, helping owners stay ahead of regulatory changes rather than reacting to them.
Ultimately, Legionella risk management is both a health issue and a business issue. Outbreaks can lead to serious consequences, including liability, reputational damage, and operational disruption. At the same time, regulatory non-compliance can result in fines, mandated corrective actions, or increased scrutiny from authorities.
The increasing pace of regulation underscores a simple point. Legionella is not just a technical issue to address after a problem occurs. It is a dynamic risk that requires proactive management. For property owners and managers, staying informed about regulatory developments and maintaining a robust, adaptable water management approach is the best way to protect both building occupants and long-term asset value.
