Updated Legionella Guidance On The Way

A supplement to ASHRAE Standard 188, the revised Guideline 12-2000R is expected to be published later this year.

By Bill Pearson, CWT
From the June 2019 Issue

ANSI/ASHRAE Standard 188, Legionellosis: Risk Management for Building Water Systems, was published in June of 2015. As a long-awaited document more than 10 years in development, it became the first, and still the only, legionellosis standard in the U.S. The release of Standard 188 eerily coincided with the largest outbreak of Legionnaires’ disease in New York history, occurring in the south Bronx of New York City. By August of 2015, investigators eventually tied the near monthlong outbreak source to a cooling tower at The Opera House Hotel in the city. Ultimately, more than 130 people were sickened with the deadly pneumonia caused by Legionella bacteria and 18 lives were lost. The NYC outbreak swiftly resulted in emergency regulations being put in place for the city and state that eventually became regulatory law at both levels.legionellosis

However, the NYC outbreak ended up with a primary, if not singular focus on cooling towers as the source of legionellosis (disease). Resultant were regulations that only applied to the existence and operation of cooling towers. This is counter to current knowledge and data that is reported and supported by researchers and subject matter experts, including the Centers for Disease Control and Prevention (CDC), that the premise-plumbing (domestic, potable) water systems of large buildings and facility complexes are the major source of legionellosis disease. It has further been emphasized that hospital water distribution systems might be the most overlooked, important, and controllable source of healthcare-associated infections (HAIs), including legionellosis. While ASHRAE Standard 188 was adopted into the NYC/NY regulations, it was only done so “in part”( sections 5, 6, and 7.2). These sections applied to cooling towers and evaporative condensers. NY and NYC regulations have since been expanded to include the potable water systems of healthcare facilities.

Quick reminder. Legionnaires’ disease—or plainly described, Legionella pneumonia—is not a “new” disease. It has not been cured, and it is both a serious and not rare disease. Since the initial outbreak in 1976 that led to the discovery and identification of Legionnaires’ disease, we have learned a lot about the bacteria (Legionella) that causes this pneumonic disease and the disease itself. This includes how Legionella pneumonia is contracted and how to reduce the risk of disease contraction, as well as modern effective medical treatments. ASHRAE Standard 188 and other guideline standards provide substantial direction and information that can be adopted to manage building water systems and devices to manage and control Legionella, reduce the incidence of disease—and, hopefully, to prevent it.

What has followed since the publication of Standard 188 and the NYC outbreak that both occurred that infamous summer of 2015, has been both an unprecedented and needed focus on Legionella and the management of this waterborne pathogen in the building water systems and devices associated with the transmission of legionellosis. This has been led, maybe arguably, by the CDC as well as other governmental organizations and authorities having jurisdiction (AHJs)—the most notable being the Centers for Medicare and Medicaid Services (CMS) —as well as related professional organizations producing updated guidance documents.

A significant realization. A great deal of information and perhaps startling realization has come to view with this focus and the resulting data and research reporting by the CDC. This has particularly been presented within the CDC Toolkit and CDC VitalSigns publications first released in June of 2016 and followed with an update in June of 2017. The most current surveillance data by the CDC shows a 17-year (2000-2017) continuing increase in the annual incidence rate of Legionnaires’ disease cases for the United States of more than 550%!

A significant directive. The CMS directive (memorandum) issued by the Department of Health & Human Services/Centers for Medicare & Medicaid Services (CMS) on June 2, 2017, is a game-changer. The directive, effective immediately, was put in place and was applicable to: hospitals, critical access hospitals (CAHs), and long-term care (LTC) facilities. It also intended to provide general awareness for all healthcare organizations.legionella guidance

It succinctly stated that CMS expects: “Medicare and Medicare/Medicaid certified healthcare facilities to have water management policies and procedures to reduce the risk of growth and spread of Legionella and other opportunistic pathogens in building water systems.” It further stated: “Facilities must have water management plans and documentation that, at a minimum, ensure each facility: Conducts a facility risk assessment to identify where Legionella and other opportunistic waterborne pathogens … could grow and spread in the facility water system; and develops and implements a water management program that considers the ASHRAE industry standard and the CDC toolkit.”

With continuing high-profile outbreaks; the release of ASHRAE Standard 188; and issuance of regulatory laws by state, city, and local authorities, as well as directives and regulations by other authorities having jurisdiction, such as CMS and The Joint Commission (TJC), there is a responsibility and there are requirements for managing Legionella as a waterborne pathogen in associated building water systems.

As directed by these AHJs, many facilities are now required to have policies in place, conduct risk assessments, implement appropriate risk management, and develop water management plans to control Legionella. All these factors have greatly influenced the way facility owners and managers operate their buildings and building water systems and how water treatment professionals design, implement, monitor, and document water treatment and water management programs.

ASHRAE Guideline 12-2000R. ASHRAE Standard 188 is a “standard” document where mandatory and code-intended “standards” language, in order to be enforceable, often limits prescriptive guidance. Standard 188 tells us “what to do” (i.e., development of a risk management process driven ‘water management plan’ (WMP) to manage Legionella and legionellosis). However, it is lacking in prescription guidance.

The long standing ASHRAE Guideline 12-2000, Minimizing the Risk of Legionellosis Associated with Building Water Systems (published in 2000), has provided subject matter guidance for many years. A long-awaited update of Guideline 12-2000 to supplement Standard 188 and serve as guidance in light of current knowledge and data is close to completion. With a title change to Managing the Risk of Legionellosis Associated with Building Water Systems, the designated Guideline 12-2000R (R for revision) has been through three public reviews and is expected to be approved and published in 2019. It has specifically been under revision by the same ASHRAE committee (SSPC) for Standard 188 to keep it in alignment with providing guidance for the development of water management programs as required by Standard 188.

So, stay tuned. And, for more on guidance on reducing the risk of Legionella, visit the ASHRAE website.

legionellosisPearson is President of BPEARSON Consulting LLC as well as a principal consultant at Arthur Freedman Associates, Inc. He is a Certified Water Technologist (CWT) with more than 40 years’ experience in the water treatment industry, specializing in Legionella risk management. Pearson currently serves as the vice chair of ASHRAE SSPC 188 and is an ASHRAE Learning Institute instructor for ASHRAE Standard 188. He is also the Association of Water Technologies liaison to ASHRAE.

Do you have a comment? Share your thoughts in the Comments section below or send an e-mail to the Editor at acosgrove@groupc.com.


  1. I was diagnosed with legionnaires 1 year ago. NJ offered no help besides 6 month disability that I paid into for over 30 year. Lost everything- homeless- no help from NJ but Snap but will lose it because I work parttime.. I’m 57 and somehow inhaled this bacterial infection. No help. Wish I didn’t wake up from induced coma. Life has been a living hell since legionnaires I know

Comments are closed.