LiquiTech Blog

Legionella Bacteria Water Sampling Methodology 

This blog delves into systematic approaches for Legionella water testing, offering valuable insights into best practices and recommendations to ensure the safety of your water. 

Importance of quarterly Legionella sampling

Building water systems are dynamic and influenced by various factors such as usage patterns, maintenance schedules, and seasonal changes in municipal water quality. These complex interactions can significantly impact water chemistry and microbiology, creating an environment where Legionella bacteria can thrive. To effectively manage and mitigate the risk of Legionella growth, it is crucial to implement regular testing protocols. Conducting quarterly Legionella testing is strongly recommended. This comprehensive approach not only captures potential seasonal fluctuations but also serves as a robust strategy to ensure the ongoing safety and maintenance of water systems. By prioritizing regular testing, building owners and operators can proactively address any emerging issues and safeguard the well-being of occupants.

Sampling methodology 

Routine sampling for Legionella should be performed to be representative of the building’s water systems. This may be based on size, number of water systems, high-risk locations, and water usage. There are a few strategies in the industry for sampling for Legionella. One method involves taking at least ten samples. Another would be to sample 10% of outlets in the building. These rules may vary depending on the system’s size, but at minimum, it should include near, mid, and far samples, as well as other representative locations. For larger structures, collecting additional samples to account for variations across different floors, water risers, and loops is advisable. This ensures a comprehensive understanding of the system’s water quality. Following this rule strikes a balance between representative sampling and obtaining sufficient data to make informed water management and maintenance decisions. 

Distal site positivity rule in healthcare

The risk of healthcare-associated Legionnaires’ disease significantly increases when 30% or more of distal hot water outlets, such as faucets and showers, test positive for Legionella bacteria. Conversely, the risk decreases if the percentage of positive outlets falls below 30%. This approach, establishing a distal site positivity rule of 30%, offers an effective and practical indicator of Legionella risk in healthcare facilities. By implementing this rule, facilities can proactively implement appropriate corrective actions based on the positivity level and utilize their water management program to enhance maintenance, monitoring, and diagnostic procedures to ensure the safety and well-being of their patients and staff. These measures will help mitigate the potential spread of Legionnaires’ disease and foster a healthier environment for all. 

Water sampling services 

LiquiTech provides water quality testing and diagnostics services on an ad-hoc basis or as an ongoing service when you partner with us. We will help you to proactively identify harmful contaminants in your building’s water system, provide easy-to-understand test results with interpretation and recommendations by certified water safety specialists, and help you navigate the Department of Health and other regulatory agencies with expert guidance. 

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