Uploaded January 2020 | Updated September 2026, 1 week ago
According to the Centers for Disease Control and Prevention (CDC), cases of Legionnaires’ disease have been on the rise in the United States. Legionnaires’ disease is a serious, and sometimes fatal, type of pneumonia caused by a type of bacteria known as Legionella, which lives in water.
People can become sick (9 in 10 CDC investigations show almost all outbreaks were caused by problems preventable with more effective water management. - CDC) when they inhale contaminated water from building water systems that are not adequately maintained (Legionnaires’ disease is deadly for approximately 1 in 10 people who get it. - CDC). This is why the CDC states buildings may need a water management program to reduce the risk for Legionnaires’ disease associated with building water systems and devices.
The agency also reports that a water management program team should be established that regularly monitors water quality parameters, such as disinfectant and temperature levels. By monitoring these parameters, the team can ensure that building water systems are operating in a way to minimize hazardous conditions that could encourage Legionella and other waterborne pathogens to grow. If the team finds that a control limit (e.g., temperature, disinfectant level) is not being met, their next step will be to take corrective actions to get conditions back to within an acceptable range.
In regard to sampling for Legionella, the CDC states the following:
Routine environmental sampling for Legionella (i.e., sampling that is performed proactively as part of an effort to reduce risk of Legionella growth and transmission in building water systems, not in the context of an outbreak investigation) is one way to validate the efficacy of a water management program (i.e., to confirm that the water management program is working as intended). The team should base decisions about routine environmental sampling for Legionella on a variety of factors, including the building environmental assessment and water quality data supporting the overall performance of the water management program. Note: The approach to routine sampling in the absence of disease may be different than the approach to environmental sampling in the context of an outbreak.
If the team decides to perform validation using environmental sampling for Legionella, they should not sample in isolation but as a part of a comprehensive water management program. The team should make specific decisions about sampling frequency, location and methodology. Sampling plans are unique to each facility and based on factors such as:
• Findings from the environmental assessment and any baseline Legionella test results
• Overall performance of the water management program, trend analysis of Legionella test results, and water quality parameters (e.g., disinfectant, temperature)
• In healthcare facilities, correlation of environmental test results with clinical surveillance data
• Building characteristics (e.g., size, age, complexity, populations served)
• Sites of possible exposure to aerosolized water
• Available resources and supplies to support sampling
These are just a few of the many things to know about Legionella and monitoring building water. To learn more about this or other building science, industrial hygiene, indoor air quality, environmental, health or safety issues, please visit the websites shown below.
Clark Seif Clark csceng.com
EMSL Analytical, Inc. emsl.com
LA Testing latesting.com
Zimmetry Environmental zimmetry.com
Healthy Indoors Magazine healthyindoors.com
According to the Centers for Disease Control and Prevention (CDC), cases of Legionnaires’ disease have been on the rise in the United States. Legionnaires’ disease is a serious, and sometimes fatal, type of pneumonia caused by a type of bacteria known as Legionella, which lives in water.
People can become sick (9 in 10 CDC investigations show almost all outbreaks were caused by problems preventable with more effective water management. - CDC) when they inhale contaminated water from building water systems that are not adequately maintained (Legionnaires’ disease is deadly for approximately 1 in 10 people who get it. - CDC). This is why the CDC states buildings may need a water management program to reduce the risk for Legionnaires’ disease associated with building water systems and devices.
The agency also reports that a water management program team should be established that regularly monitors water quality parameters, such as disinfectant and temperature levels. By monitoring these parameters, the team can ensure that building water systems are operating in a way to minimize hazardous conditions that could encourage Legionella and other waterborne pathogens to grow. If the team finds that a control limit (e.g., temperature, disinfectant level) is not being met, their next step will be to take corrective actions to get conditions back to within an acceptable range.
In regard to sampling for Legionella, the CDC states the following:
Routine environmental sampling for Legionella (i.e., sampling that is performed proactively as part of an effort to reduce risk of Legionella growth and transmission in building water systems, not in the context of an outbreak investigation) is one way to validate the efficacy of a water management program (i.e., to confirm that the water management program is working as intended). The team should base decisions about routine environmental sampling for Legionella on a variety of factors, including the building environmental assessment and water quality data supporting the overall performance of the water management program. Note: The approach to routine sampling in the absence of disease may be different than the approach to environmental sampling in the context of an outbreak.
If the team decides to perform validation using environmental sampling for Legionella, they should not sample in isolation but as a part of a comprehensive water management program. The team should make specific decisions about sampling frequency, location and methodology. Sampling plans are unique to each facility and based on factors such as:
• Findings from the environmental assessment and any baseline Legionella test results
• Overall performance of the water management program, trend analysis of Legionella test results, and water quality parameters (e.g., disinfectant, temperature)
• In healthcare facilities, correlation of environmental test results with clinical surveillance data
• Building characteristics (e.g., size, age, complexity, populations served)
• Sites of possible exposure to aerosolized water
• Available resources and supplies to support sampling
These are just a few of the many things to know about Legionella and monitoring building water. To learn more about this or other building science, industrial hygiene, indoor air quality, environmental, health or safety issues, please visit the websites shown below.
Clark Seif Clark csceng.com
EMSL Analytical, Inc. emsl.com
LA Testing latesting.com
Zimmetry Environmental zimmetry.com
Healthy Indoors Magazine healthyindoors.com
