Legionella Testing 101: Leveraging Water LIMS for Effective Legionella Testing

Water LIMS for Legionella Testing in Drinking Water

One in every ten persons diagnosed with Legionnaires’ disease dies from it. The statistics are worse for those whose immunity is compromised. Close to 10,000 cases of Legionnaires’ disease were reported in 2018. However, as per the Centers for Disease Control & Prevention (CDC), most cases of Legionnaires’ disease are either undiagnosed or not reported. Hence, the figure could be 1.8-2.7 times higher.

What is Legionella?

Legionella is a type of gram-negative bacteria that poses serious health risks when present in drinking water systems. Legionella is responsible for a diverse range of illnesses collectively referred to as Legionellosis, where the most prevalent form is Legionnaires’, a severe type of pneumonia. Legionnaires’ disease outbreaks have been associated with polluted water sources in different environments, such as residential areas, medical facilities, and public establishments. A sputum culture or urinary antigen test are the common diagnostic tools, and antibiotics are the standard treatment for Legionnaires’ disease. About 10% of healthy individuals and 25% of those with low immunity are likely to die from the disease.

Legionella testing plays a crucial role in identifying potential hazards and preventing deadly infections. This blog explores the importance of Legionella testing in drinking water, the testing process, and the significance of regular monitoring of water systems.

Understanding Legionella and its Health Risks

Legionella bacteria are naturally present in freshwater environments like lakes and rivers, but they can also flourish in artificial water systems constructed by humans, such as plumbing networks, cooling towers, hot tubs, and ornamental fountains. The bacteria is transmitted when contaminated water droplets or mist is inhaled. This can lead to severe respiratory symptoms and, in some cases, fatalities.

Risk Factors

Legionella bacteria thrive within a temperature range of 20°C to 60°C (68°F to 140°F). Hot tubs, typically maintained between 30°C and 35°C (86°F to 95°F), create an ideal environment for Legionella to flourish and multiply.

Stagnant water in unused offices, hotel rooms, or buildings provides a breeding ground for Legionella growth. In such conditions, scale, sludge, and amoeba can develop within the pipes, offering protection and nutrients to the bacteria, and accelerating their growth and spread.

Immunocompromised people such as the elderly, convalescents, those using respiratory equipment, smokers, patients who recently had surgeries, and infants are at increased risk of infection if exposed to Legionella-contaminated water.

Legionella growth in drinking water poses a significant health risk, especially to vulnerable individuals. Understanding the causes of Legionella growth allows us to implement preventive measures effectively. Proper temperature control, eliminating stagnant water, and regular cleaning and disinfection are vital steps in ensuring safe drinking water and preventing Legionnaires’ disease outbreaks. 

The Importance of Legionella Testing

Legionella testing offers the following benefits:

  • Early Detection: Regular testing helps identify the presence of Legionella in drinking water systems early on, allowing prompt action to prevent potential outbreaks.
  • Compliance: Certain jurisdictions and regulatory bodies require specific facilities, such as healthcare institutions and hospitality establishments, to conduct routine Legionella testing to ensure compliance with safety standards.
  • Protecting Vulnerable Groups: Immunocompromised individuals, the elderly, and those with respiratory conditions are particularly susceptible to Legionnaires’ disease. Testing helps protect these vulnerable populations from exposure to contaminated water sources.

The Legionella Testing Process

The CDC provides guidance for routine testing of Legionella. Testing serves both routine and non-routine purposes, such as establishing performance indicators, validating water management plans (WMPs), evaluating potential sources of growth and transmission, confirming the success or failure of remedial treatments, and investigating environmental exposure sources for disease-prone individuals. Certain facilities, such as those housing at-risk individuals or those with a history of Legionnaires’ disease cases, may benefit from routine testing.

  • Sampling: Trained professionals collect water samples from various sampling points in the drinking water system, including faucets, showerheads, and cooling towers. Afterward, the samples are packaged and shipped to an accredited laboratory for analysis. The sampling plan should represent the entire building water system, and the volume of water collected may vary based on the source type and condition. Following the guidelines from the CDC and other accredited bodies is crucial for effective sampling.
  • Laboratory Analysis: Various laboratory considerations and test methods are available for Legionella testing. Some tests can be performed onsite, while others may require commercial laboratory involvement. Test methods can vary depending on the water system type and the reason for testing. Traditional culture (spread plate) and PCR are commonly used methods. Traditional culture detects viable bacteria and provides isolates for further characterization, while PCR detects Legionella-specific DNA or RNA but cannot differentiate between live and dead bacteria. Alternative and novel methods should be validated and verified against standard methods before they are used for testing samples.
  • Interpreting Results: Based on the laboratory findings, the concentration of Legionella bacteria is measured in colony-forming units per liter (CFU/L) if traditional culture is used or genomic units (GU) if the PCR technique is used. This data is then compared to established guidelines and standards to determine if remedial action is necessary.
    Legionella testing results alone do not indicate health risks or predict disease. There is no “safe” level or type of Legionella. Results should be interpreted considering the concentration, extent of colonization, and specific Legionella types. The presence of any Legionella should trigger appropriate response activities. Public health investigations should always be carried out in collaboration with the appropriate authority having jurisdiction.

Deploy a Water LIMS For Swift & Accurate Legionella Testing

A cloud-hosted Water Laboratory Information Management System (LIMS) provides significant advantages for Legionella testing labs. With a LIMS hosted in the cloud, laboratories conducting Legionella testing can efficiently manage and streamline their workflows. A cloud-based water LIMS allows easy access to data and test results from any location and at any time, enabling real-time collaboration between different stakeholders involved in Legionella testing. A LIMS also helps generate certificates of analysis (CoA) that can be customized based on the reporting requirements of labs. Furthermore, some water LIMS systems have an in-built quality management system that flags erroneous test results and helps trace quality control issues as soon as they are detected, assuring high-quality, accurate, and valid test results. 


Legionella testing in drinking water is a vital aspect of maintaining public health and safety. Regular monitoring, early detection, and prompt remedial actions can prevent the spread of Legionnaires’ disease and protect vulnerable populations. Labs can ensure accurate testing and reporting of test results in a fast turnaround by deploying a cloud-based water LIMS.

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