Legionella Testing Services

Legionnaires’ disease is wholly preventable by reducing exposure to Legionella bacteria. Routine Legionella testing is the only way to understand the exposure risk and is a vital part of any facility’s water management. It is impossible to take action without understanding if bacteria is present in water systems.

ASHRAE Standard 188-2021: Legionellosis: Risk Management for Building Water Systems establishes the minimum risk management requirements for building water systems. The standard highlights the requirements of Water Management Plans(WMP’s) which include a Confirmation section. This section requires facility managers and owners to establish required procedures that verify the WMP controls the hazardous condition throughout building water systems (i.e. Legionella bacteria). This is called the validation of the plan.

Routine monitoring will help to validate the success of your implemented water management plan or show where you need to improve when you reassess. Proactive, routine testing is the only way to be LegionellaREADY. 

Types of Legionella Testing

The types of tests we are able to provide at ChemREADY through our partners include: 

  • Culture (Gold standard –11-14 days) with and without serogrouping
  • Legiolert(Modified culture –7 days) 
  • qPCR (2-48 hours) 
  • Swabs (Investigation) 
  • Test strips 
  • Monitoring Equipment

We work with certified microbiology laboratories that work frequently with healthcare, hospitality, and industrial facilities to provide multiple testing options for Legionella. Their testing protocols compare disease risk with Legionella culture results and the extent of contamination within the tested environment. 

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.

Frequency of Legionella Testing

Many facility managers look for recommendations on how many and how often tests should occur. Every building has water systems and features unique to it. It is important to know that while Legionella bacteria are not in every building, studies show that up to 50% of buildings contain the bacteria in their water systems. It can exist in both potable and non-potable water systems. Facility managers must understand this risk by performing a risk assessment. The risk assessment will highlight 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 should consider sampling enough points to represent each water system.

Examples include:

  • Potable hot water system – Quarterly testing a minimum of 10 samples including a minimum of two samples per floor, different types of fixtures representing near, mid, and far points from the central recirculation loop. Include drinking fountains, ice machines, and hot water tanks.
  • Cooling Tower systems – Monthly testing each cooling tower basin while in operation based on the American Industrial Hygiene Association recommendations and best practices.
  • Decorative Fountains – Monthly testing in summer months with quarterly testing in cooler months.

Each facility has different risks associated with each system dependent upon water quality characteristics, routine maintenance activities, and the history of the system.

In order to correctly navigate your system, contact our Legionella consultants today to consider the risks of your facility.

How To Collect Legionella Samples

When taking a sample from potable outlets, it’s important not to flush the line prior to sample collection. Flushing the line can lead to inaccurate test results not representative of actual system conditions. The sample bottle must have a sodium thiosulfate tablet obtained from laboratory (0.1N solution). This inactivates chlorine in water and provides more accurate results. Log the date, time, and location for the sample.

Potable water: First draw into bottle. Second bottle analyze for pH, L, TDS, Free Cl-, temperature. 

Cooling Tower: Sump, away from chemical injection and not after normal biocide schedule. 

Other water fixtures: Timed away from disinfection chemicals, most representative sample. 

If you are unsure how to properly obtain samples for validation testing, contact one of our Legionella experts at ChemREADY.

Positive Legionella Results

It's important to have a plan after a positive Legionella test result.

Getting a positive Legionella test in your water system is not the kind of news any facility wants to hear, but there are steps you can take to mitigate the situation and protect the people on your site. Although a positive test is a distressing information, the good news is that you’re aware of this early on exactly because you implemented testing for Legionella. Proactive testing is the most important thing you can do to protect the people around you.

The first step upon getting any positive Legionella hit is to consult your Water Management Plan(WMP). If you don’t have a plan, you should consider creating one, and healthcare facilities are required by the Centers for Medicare and Medicaid Services (CMS) and the Joint Commission to maintain one. Your water management plan should clearly spell out the steps to take when you determine that your water system contains Legionella.

The CDC has suggested activities when Legionella results show poorly controlled or uncontrolled growth:

  1. Review procedure for laboratory sample collection, handling, and testing for potential errors.
  2. Verify that the water system equipment is in good working order and operating as intended.
  3. Perform records review to verify that the WMP is being implemented correctly.
  4. Verify operating conditions, such as physical and chemical characteristics of incoming water and facility water systems.
  5. Re-evaluate aspects of the WMP, including a risk assessment, cleaning, maintenance procedures, chemical treatment, and other aspects that could affect Legionella testing.
  6. Correct deficiencies by adjusting WMP as necessary.
  7. Consider whether remediation is required after performing first six steps.
  8. If remediation is performed, wait at least 48 hours after the system returns to normal before retesting for Legionella.

If poorly or uncontrolled growth of Legionella occurs in healthcare facilities or facilities with populations at increased risk, consider implementing immediate control measures such as installing Point-Of-Use Filters to protect people from exposure concurrently while implementing the guidance above.

CDC’s Interpretation of Positive Legionella Results

The CDC published guidance in 2021 regarding positive Legionella test results.

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.