Legionnaires’ disease is entirely preventable by minimizing exposure to Legionella bacteria. Routine Legionella testing is essential for understanding exposure risk and is a vital component of any facility’s water management plan. Without knowing whether bacteria are present in your water systems, it’s impossible to take corrective action.
ASHRAE Standard 188-2021: Legionellosis: Risk Management for Building Water Systems sets the minimum risk management requirements for building water systems. This standard emphasizes the need for Water Management Plans (WMPs), which include a Confirmation section. This section requires facility managers and owners to establish procedures that verify the WMP’s effectiveness in controlling hazardous conditions in building water systems, including Legionella bacteria. This process is known as the validation of the plan.
Routine monitoring is crucial to validate the success of your water management plan or to identify areas needing improvement during reassessment. Proactive, routine testing is the only way to be truly LegionellaREADY.
At ChemREADY, we offer various Legionella testing services through our certified microbiology laboratory partners, including:
These laboratories frequently collaborate with healthcare, hospitality, and industrial facilities to provide multiple testing options for Legionella. Their testing protocols compare disease risk with Legionella culture results and assess the extent of contamination in the tested environment.
Given the variety of testing options available, it’s essential to consult with our Legionella consultants to determine the best solution for your facility.
There are a variety of options of testing to consider for your facility. In order to understand the best solution for your facility, contact our Legionella consultants today.
Facility managers often ask how many tests should be performed and how frequently. While Legionella bacteria are not present in every building, studies show that up to 50% of buildings may have Legionella in their water systems. This bacteria can exist in both potable and non-potable water systems. To understand the risk, a risk assessment should be performed, highlighting the potential for poorly controlled or uncontrolled Legionella growth in each system.
Based on the risk assessment, a routine sampling plan should be developed by facility managers. This plan should include sufficient sampling points to represent each water system.
Examples include:
Each facility’s risks vary based on water quality characteristics, routine maintenance activities, and the history of the system.
When collecting samples from potable outlets, do not flush the line before sampling, as this can lead to inaccurate test results that don’t reflect actual system conditions. The sample bottle should contain a sodium thiosulfate tablet from the laboratory (0.1N solution) to inactivate chlorine in the water, ensuring more accurate results. Record the date, time, and location of each sample.
Sample Collection Guidelines:
If you are unsure how to properly collect samples for validation testing, contact one of our Legionella experts at ChemREADY.
A positive Legionella test result is concerning, but proactive steps can be taken to mitigate the situation and protect those on-site. The key is to follow your Water Management Plan (WMP). If you don’t have one, consider creating one, especially since healthcare facilities are required by the Centers for Medicare and Medicaid Services (CMS) and the Joint Commission to maintain a WMP. Your plan should clearly outline the steps to take when Legionella is detected in your water system.
The CDC recommends the following actions for poorly controlled or uncontrolled Legionella growth:
For healthcare facilities or those with high-risk populations, consider implementing immediate control measures, such as installing Point-of-Use Filters to protect against exposure while following the above guidance.
Historically, the Centers for Disease Control and Prevention(CDC) had no official stance on the results of Legionella testing. 2021 marked the first year they published guidance for the public. The CDC’s graphic “Figure 1. Routine Legionella testing: A multifactorial approach to performance indicator interpretation” highlights four areas of consideration for Legionella testing results. The first section discusses which concentration indicates that Legionella growth appears uncontrolled, poorly controlled, or well controlled. Concentrations expressed as CFU/mL are for test results by traditional plate culture methods. If other test methods are used, consult an expert for interpretation.
The detection of greater than or equal to 10 CFU/mL in potable water or the detection of greater than or equal to 100 CFU/mL in non-potable water indicates that Legionella growth appears uncontrolled.
The detection of 1.0-9.9 CFU/mL in potable water or the detection of 10-99 CFU/mL in non-potable water indicates that Legionella growth appears poorly controlled.
The detection of any to 0.9 CFU/mL in potable water or the detection of any to 9 CFU/mL in non-potable water indicates that Legionella growth appears well controlled.
No Legionella detected also indicates that Legionella growth appears well controlled, and is a stronger indication that Legionella is well controlled than detection of any Legionella.
The second section relates to the way in which concentration change over time indicates that Legionella growth appears uncontrolled, poorly controlled, or well controlled.
A 100-fold or greater increase in concentration (for example, an increase from 0.7 CFU/mL to 70 CFU/mL) indicates that Legionella growth appears uncontrolled.
A 10-fold increase in concentration (for example, an increase from 0.7 CFU/mL to 7 CFU/mL) indicates that Legionella growth appears poorly controlled.
Steady Legionella concentration (for example, 0.7 CFU/mL for two consecutive sampling rounds) indicates that Legionella growth appears well controlled.
The third section relates to the way in which extent of colonization indicates that Legionella growth appears uncontrolled, poorly controlled, or well controlled. The fourth section relates to the way in which type of Legionella, such as species and serogroup, are associated with Legionnaires’ disease.
For a complete interpretation, visit our (insert link) Legionella resources page and find resources by the CDC.
Legionella testing involves analyzing water samples to detect the presence of Legionella bacteria, which can cause Legionnaires’ disease. It is a critical component of water safety and management plans.
Routine testing is essential to validate the effectiveness of your Water Management Plan and to identify areas where Legionella bacteria may be present, allowing for timely corrective action.
The frequency of testing depends on your facility’s specific risks, as determined by a risk assessment. Potable water systems may require quarterly testing, while cooling towers may need monthly testing.
If you receive a positive test result, consult your Water Management Plan for guidance on corrective actions. The CDC recommends a series of steps to address poorly controlled or uncontrolled Legionella growth.
When collecting samples, avoid flushing the line beforehand, use a sodium thiosulfate tablet in the sample bottle, and follow specific guidelines for different water systems. Contact ChemREADY for detailed instructions.
