"Our goal is not zero Legionella pneumophila bacteria. Our goal is zero cases." – Patsy Root

Legionella risk becomes harder to manage when building teams treat every detection as equivalent—or collect samples without first deciding what a positive result will trigger. Patsy Root, Senior Manager of Government Affairs at IDEXX Water, explains how a clear water management program can replace uncertainty with defined responsibilities, routine monitoring, and proportionate action.

Focus Testing on the Organism of Concern

Patsy distinguishes between the broader group of Legionella species and Legionella pneumophila, the organism she recommends prioritizing during routine monitoring. She reviews research indicating that detecting non-pneumophila Legionella does not automatically mean L. pneumophila is present.

That distinction matters operationally. Remediation can require significant time, money, facility disruption, and lost revenue. Testing targets and corrective actions should reflect public-health risk rather than a generalized fear of any Legionella detection.

The goal is management, not eradication. A well-designed program aims to prevent disease while recognizing that completely eliminating the organism from every water system is not realistic.

Define the Response Before Sampling

Questions about routine monitoring remain among the most common Patsy receives: Where should samples be collected? How often should testing occur? Which laboratory and method should be used? What actions should follow a positive result?

When reviewing a positive laboratory report, determine whether L. pneumophila was detected, its concentration, how many locations tested positive, and whether those locations are clustered or distributed throughout the building. Then compare the findings with the action limits and response procedures established in the water management program.

Testing without a response plan can create unnecessary confusion. Likewise, writing a program does not protect a facility unless the assigned monitoring, flushing, temperature checks, chlorine residual measurements, documentation, and corrective actions are consistently completed.

Connect Water Treatment, Exposure, and Ownership

A conventional water treatment program designed for heat-transfer efficiency does not automatically address every public-health exposure route. Building teams must consider where people could encounter aerosolized or otherwise unsafe water—not only whether treatment chemistry is operating as intended.

Patsy uses a milk-jug analogy to explain building ownership. Farmers, processors, transporters, and grocery stores maintain milk until it is purchased. Once the customer brings it home, however, that customer becomes responsible for storing it safely. Likewise, once water passes through the meter, the building owner becomes responsible for maintaining its quality.

A comprehensive water management team may require a decision-maker with financial authority, a water treatment professional, plumbing expertise, maintenance and facilities personnel, and representatives from housekeeping, kitchens, or infection prevention where applicable.

Communication with the public water system can also provide essential context about the incoming water source, seasonal temperature, distribution conditions, and disinfection. For water professionals advising building owners, the leadership challenge is translating risk information into repeatable actions that every responsible person understands and can sustain.

Listen to the full conversation above. Explore related episodes below. Stay engaged, keep learning, and continue scaling up your knowledge!

Timestamps

02:00 — Trace Blackmore shares how Legionella Awareness Month began in 2020, why the topic continues to evolve, and why these episodes remain among the podcast's most downloaded and shared.

04:56 — Trace introduces returning guest Patsy Root, Senior Manager of Government Affairs at IDEXX Water, and revisits her appearances in Episodes 403 and 434.

06:25 — Interview with Patsy Root about Legionella pneumophila testing, effective water management programs, professional education, and building-water responsibility.

08:50 — Patsy explains why Legionella education remains necessary six years after the pandemic highlighted the risks associated with reopening stagnant building water systems.

10:40 — Foundational Legionella education should be adapted to an audience's experience, responsibilities, and understanding of microbiology.

13:35 — AWT conferences and professional communities connect new practitioners with experienced professionals whose field knowledge may not appear in books or technical papers.

16:10 — Patsy explains how professional collaboration helps the industry reassess long-standing assumptions about Legionella species and focus more precisely on L. pneumophila.

20:20 — Patsy discusses how CWT and ASSE 12080 certifications are understood outside the water treatment industry and why credentials should be evaluated alongside experience, references, and work products.

23:20 — Research from KWR, the World Health Organization, and the Journal of Hospital Infection challenges the use of non-pneumophila Legionella as an indicator for L. pneumophila.

27:10 — Patsy distinguishes water management from eradication and explains why the objective should be zero disease cases rather than zero Legionella bacteria.

29:40 — Legionella longbeachae is associated primarily with soil, potting mix, and compost, illustrating why professionals must consider the environmental context of published research.

31:20 — Routine monitoring questions—where, when, how, and what to test—remain the questions Patsy receives most frequently from facility teams and water professionals.

32:30 — Sustainable implementation depends on teaching everyone responsible for the program what to do and why each activity matters.

34:30 — Patsy challenges the belief that avoiding Legionella testing eliminates risk and explains why routine verification remains necessary even when treatment measures are in place.

37:10 — A conventional water treatment program may support heat-transfer efficiency without addressing every point where people could be exposed to unsafe water.

38:40 — Patsy shares the milk-jug analogy to explain why a building owner becomes responsible for water quality after the water passes through the meter.

42:00 — Patsy discusses the regulatory gap surrounding water inside many buildings and the need for persistent education, communication, and outreach to building owners.

46:20 — Legionella requirements are beginning to appear in insurance policies as insurers and building owners recognize the financial consequences of outbreaks.

48:40 — Accurate outbreak reporting should explain transmission, exposure routes, risk factors, and reliable sources of public-health information without creating unnecessary panic.

51:20 — Patsy outlines how to interpret a positive laboratory result by reviewing the organism, concentration, number of positive locations, distribution, and established action limits.

54:00 — Sampling should not begin until the facility knows how it will respond if Legionella is detected.

55:30 — A cross-functional water management team should include financial authority, water treatment knowledge, plumbing expertise, facilities personnel, and representatives familiar with potential exposure areas.

58:30 — Stronger collaboration between public water systems and building water management teams can clarify incoming water conditions and each party's responsibilities.

1:02:00 — Patsy answers four Legionella Awareness Month questions about management, trusted resources, common implementation failures, and the value of focusing on L. pneumophila.

1:04:00 — Trace shares the episode discussion guide and the Scaling UP! H2O Legionella Resources Library for professionals reviewing the topic with their teams.

1:07:00 — Words of Water with James McDonald

Quotes

"It's important to have everybody at the table, make sure everybody understands not only what they're doing, but why they're doing it."

"Don't test the water for Legionella bacteria until you know what you're going to do if it comes back positive."

"The housekeeping person's not going to think like the plumber, and the plumber's not going to think like the infection person, and the finance person's going to think differently, too."

"Having a water management program does not absolve you from the daily or weekly activities that are required to be done. It must be done for it to be effective."

Connect with Patsy Root

Phone: (207) 523-0835

Email: patsy-root@idexx.com

Website: IDEXX: Overview | LinkedIn

LinkedIn: Patsy Root | LinkedIn

Guest Resources Mentioned

World Health Organization — Legionella and the Prevention of Legionellosis

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