Legionella is a type of bacteria that is found in water and wet environments. Under the right conditions, it can grow in the plumbing of buildings or in water features. When people inhale water droplets containing Legionella from sources such as showers, hot tubs, cooling towers, or medical equipment, they can develop Legionnaires’ disease, a serious and sometimes fatal type of pneumonia.
People over the age of 50, those with chronic lung conditions or weakened immune systems, and people who smoke or used to smoke are especially at risk for Legionnaires’ disease.
Having an effective water management program can help control these causes and decrease Legionella growth.
All buildings carry some risk of growing and spreading Legionella, but some buildings and components are more likely to than others. Even buildings using public water with an added disinfectant can have Legionella growth.
Building features like cooling towers, hot tubs, whirlpool spas and decorative fountains are often responsible for Legionella outbreaks. They often keep water features in the favorable Legionella growth zone of 77°F to 113°F and create water droplets that someone can breathe in.
Large buildings with complex water systems
Large buildings with complex water systems include hotels, bed and breakfasts, hospitals or condominiums. Because of the building’s size, it can be difficult to maintain high enough water temperatures and disinfectant levels, or to make sure taps and fixtures are regularly flushed. Large buildings may also have fixtures or devices that require regular servicing (for example, cooling towers, hot tubs, decorative fountains).
Health care settings
Hospitals, long-term care facilities, and other health care facilities serve populations that are especially vulnerable to Legionella infections. Health care settings are required by the Centers for Medicare and Medicaid to have water management programs to reduce the growth and spread of Legionella.
Buildings with variable or seasonal occupancy
In buildings with variable or seasonal occupancy, Legionella can grow in the plumbing during periods of low use.
Preventing the conditions that allow Legionella to grow is the best way to reduce the risk of Legionnaires disease. The Centers for Disease Control and Prevention (CDC) recommends that buildings with complex water systems develop a water management program.
Water management programs (WMPs) help to identify areas and devices in buildings where Legionella growth, spread or transmission may occur and detail strategies on how to prevent it. WMPs are now the industry standard for many buildings in the United States to minimize the risk for Legionella and other germs associated with a building’s plumbing.
Take this free training on how to prevent Legionella growth and how to develop or improve a water management program for your building.
The CDC recommends following a 7-step framework when developing a WMP. Below are summaries of each step and a direct link to that step in the CDC’s toolkit for more detailed information. We’ve also included some tips and questions for you to consider as you are developing your WMP.
Download the CDC’s full toolkit: Developing a Water Management Program
Clearly define who is on the team and which tasks they are responsible for. The number of people and who is on the team will vary depending on the size of the building, what types of devices and plumbing fixtures are present, and the type of setting (health care versus hotel).
Use detailed diagrams and schematics to trace the flow of water from the point of entry to all outlets and fixtures.
Look for locations where water may stagnate, places where temperatures are between 77°F and 113°F, and for devices that produce mists or splashing (aerosols).
Use the CDC’s Legionella Control Toolkit to identify how to limit the growth and spread of Legionella (for example, flushing, cleaning, disinfecting) at each of the areas identified in Step 3. This toolkit includes information for potable water systems as well as high risk sources like cooling towers and hot tubs.
The CDC also outlines considerations for systems that use non-potable water, which is water not used for drinking or showering.
Take corrective actions when needed. Have a written plan for how to respond when control limits are not met, like flushing, disinfection, or increasing temperatures. For example:
Make sure staff are correctly implementing the program.
Be sure to update the program documentation as your water system changes and requires different control points, control measures and corrective actions.
ASHRAE Standard 188 and ASHRAE Guideline 12 offer detailed building-specific guidance that is recommended for all large buildings. The CDC also has an accompanying guide on how to implement this framework.
Consider working with a Legionella consultant if you need help developing your water management plan or identifying solutions for your facility.
To help prevent Legionella growth, we recommend regularly following these best practices:
Flushing Protocols
Preventive Maintenance
Temperature Monitoring and Use of Mixing Valves
Disinfectant Residual
Environmental Assessment
Environmental Testing
Periodically test for Legionella in high-risk areas or during outbreak investigations.
Communication
Special Considerations
If you need a water management program or an environmental assessment for your building, consider working with a Legionella consultant. The CDC offers advice on things to consider when selecting a consultant.
