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How to Protect Against Legionella

July 19, 2012

Is your water safe? A new standard can help safeguard against a Legionella outbreak. It can lurk in your cooling towers, piping systems, showerheads, hot tubs, sauna rooms, and decorative fountains. It causes flu-like symptoms, hospitalizations, lingering neurological issues, and death. Legionella bacteria begin as a microscopic presence in your water systems and can balloon into a tarnished business image, a CDC investigation, and lengthy lawsuits.

It can lurk in your cooling towers, piping systems, showerheads, hot tubs, sauna rooms, and decorative fountains. It causes flu-like symptoms, hospitalizations, lingering neurological issues, and death. Legionella bacteria begin as a microscopic presence in your water systems and can balloon into a tarnished business image, a CDC investigation, and lengthy lawsuits.

“Though some facilities are proactive with water management, many building teams struggle with documentation or do not have a clearly identified team responsible for the water system,” observe ASHRAE members Bill McCoy of Phigenics and William Pearson of Southeastern Labs. The forthcoming ASHRAE Standard 188, Prevention of Legionellosis Associated with Building Water Systems, is a significant step toward formalized Legionella prevention.

The standard will require a new process to document proactive measures against Legionella with a Hazard Analysis and Critical Control Point (HACCP) risk management plan. The goal is to establish which control and monitoring measures your building has in place.

“We know how to analyze and control this hazard. But we need a standardized practice to specify for facility managers and owners exactly what to do in their facilities to control the hazard in a systematic and scientifically defensible way,” McCoy and Pearson explain. “ASHRAE Standard 188P is intended to fulfill this need.”

Whether you choose to adhere to the standard or not, preventing Legionella from breeding in your water system requires a proactive stance. Remember that building water safety and quality are not within the jurisdiction of the public water utility – the responsibility is yours. Use these three components of the standard to fulfill your General Duty Clause. 

1) Know Thy Enemy
Legionella is a type of bacteria that causes two forms of pneumonia – Legionnaires’ disease and Pontiac Fever (collectively referred to as Legionellosis). Both conditions develop when the bacteria is inhaled through water droplets or vapor. The disease is not communicable and does not occur if Legionella is ingested.

According the Center for Disease Control (CDC), anywhere from 8,000 to 18,000 cases are reported in the U.S. each year. Because the disease is hard to distinguish from community-acquired pneumonia and the onset of symptoms occurs several days after contact, many more incidences may go unnoticed. The bacteria are most likely to affect those with weakened immune systems, including children, those with diminished lung capacity, the elderly, and people with autoimmune disorders.

The CDC estimates that 5-30% of Legionnaires’ victims perish. Many patients recover with the aid of antibiotics, but some require hospitalization for days. A growing number of reports also show that victims can have lasting neurological damage, largely affecting memory and muscle control.

Along with other waterborne diseases such as giardiasis and cryptosporidiosis, Legionella costs the healthcare system up to $539 million annually, according to CDC research. By using insurance claims, the CDC calculated that Legionnaires’ disease places a $101-321 million burden on patients, insurers, and taxpayers. For example, a single hospitalization for Legionnaires’ averages more than $34,000.

Are You At Risk?

While all commercial buildings are vulnerable to Legionella, the following risk factors can increase the likelihood of contamination:

  • Multiple housing units with one or more centralized water heaters
  • More than 10 stories high (including any levels that are below grade)
  • An inpatient healthcare facility
  • Occupants who are primarily 65 years or older
  • One or more whirlpools and/or spas
  • Any water features or devices that release aerosols, such as ornamental fountains, misters (atomizers), air washers, or humidifiers
  • Total residual halogen concentration of the incoming potable water supply is less than 0.5 mg/L (0.5 ppm) as Cl2 (chlorine).


Unlike a slip and fall incident, there’s no specific statute of limitations for Legionella. Time is of the essence for a victim to medically document the disease and connect the source of contamination to a specific location.

But once an incidence has been traced back to your building, many more reports can follow in its wake. It is the likelihood of a severe reaction to Legionella that requires the proactive attention of building managers.PageBreak 

2) Understand the Role of Your Water Systems
Beyond obvious places like cooling towers and hot tubs, there are many areas in a building vulnerable to Legionella, cautions Simon Turner, president of Healthy Buildings, a consulting firm that specializes in indoor environments. These include drinking water systems, hot water tanks, showers, misters, ice machines, fire sprinklers, and water features such as decorative fountains and water walls. Even respiratory devices and humidifiers in healthcare settings have been called into question.

The likelihood of Legionella doesn’t necessarily depend on the type of water system in question, but the conditions within that water supply. Miniscule amounts of the bacteria won’t make anyone sick, but certain environments will promote Legionella to breed at dangerous levels.

“Legionella will flourish under three conditions,” says Turner. “It needs an optimum growth temperature between 95-115 degrees F., the presence of biofilm to provide a source of nutrients, and an accumulation of sediment or scale that will shield it from chlorination.”

A major source can be dead legs in plumbing lines, which are common in older buildings with renovations or restrooms with waterless urinals. “Water becomes stagnant in these abandoned pipes and can’t be properly sanitized or flushed out, yet it will constantly seed the rest of the plumbing system with Legionella,” Turner explains.

“Owners may not be aware that they need to be prepared to respond to specific events that can push the bacteria into the rest of the water supply or cause it to grow rapidly, like water main breaks or shutdowns,” says Matt Freije, ASHRAE member and president of HC Info, a consulting firm for Legionella prevention. 

3) Develop a Risk Management Plan
One of the greatest impacts of Standard 188P is the recommendation of a HACCP risk management plan. The HACCP approach was first developed by NASA and then adapted to industries such as food safety, munitions, and automotive manufacturing. Its purpose isn’t to prevent Legionella, but to verify that the control measures to address the bacteria are in place and effective.

As outlined by the standard draft, a Legionella HACCP plan includes the following stipulations for building

  1. Conduct a hazard analysis.
  2. Determine the critical control points (CCPs).
  3. Establish critical limits for each critical control point.
  4. Establish a system to monitor control of the critical control points.
  5. Establish the corrective action to be taken when monitoring indicates that a particular CCP is not under control.
  6. Establish procedures for verification to confirm that the HACCP system is working effectively.
  7. Establish documentation concerning all procedures and records appropriate to these principles and their application.

Before you can set a HACCP plan in motion, you must have an accurate overview of your building’s water system with accurate process diagrams and schematics.

“This activity is hugely productive because the way in which water is processed in many facilities has never been schematically described, is generally unknown to the facility manager/owner, and many facility managers/owners usually do not think about the fact that the water they purchase is actually being processed in their facility,” state McCoy and Pearson.

If you don’t have water process schematics in place, you may seek an outside consultant to create them, advises Turner. They can also assist with developing a maintenance plan based on their findings that can be incorporated into the regular duties of your staff.

Steps 3-5 help identify areas of concern within your water management system and the corresponding controls that will strengthen those points. You must identify any methods used to monitor the control and how often you verify that the control is functioning properly.

“Note that this is all regarding the applied hazard control, not the hazard itself,” McCoy and Pearson stress. “As an example, if chlorine is used to control the hazard, then the team must decide and document what chlorine concentration range to apply (this is the critical control limit), the method used to measure the chlorine, the frequency that the chlorine concentration will be measured using that method, and exactly what the facility staff will do if measurements indicate that the chlorine concentration is outside the critical control limit (this is the corrective action).”

Famous Cases of Legionellosis Outbreaks

Las Vegas (2011-2012) – Over the course of a year, two MGM properties (the ARIA and Luxor resorts) were linked to Legionella cases with one fatality. Both sites had water management programs in place prior to the incidences.

Playboy Mansion (2011) – Close to 200 conference-goers who attended an evening soiree at the Mansion developed Legionnaires’ or Pontiac Fever. Bacteria in the hot tubs were identified as the culprit and a fog machine was also suspected, though never confirmed.

Unidentified Wisconsin Hospital (2010) – Eight people, none of whom were inpatients, became ill from a decorative water feature in the hospital’s lobby. The bacteria were contracted by delivery personnel and visiting family.

Stadium Place (2009) – Legionella struck eight residents at this Baltimore retirement community with one fatality. To remedy the outbreak, the water temperatures were elevated above 130 degrees F.

Bellevue-Stratford Hotel (1976) – First documented outbreak of the disease. Guests at an American Legion convention at the hotel contracted the bacteria – over 200 attendees became ill and 34 perished. The exact source of the contamination was never identified, though the air conditioning system and the cooling tower were likely sites.

Once the plan is established, validation and verification documentation is recommended. You must prove that you have controls in place and that your plan is implemented on a routine basis.

“Examples of verification are minutes from team meetings, accurate up-to-date documentation of the plan, a regular update schedule for the plan, log books showing hazard control monitoring results, and log books showing corrective actions taken,” note McCoy and Pearson. “Verification must also include reassessment of the plan on a regular basis, such as annually.”

For many owners, preventive Legionella measures will include modifying maintenance procedures. If you have a new building development, many CCPs can be included before the facility opens.

“It’s crucial to account for Legionella in the design of new buildings or renovation projects so control measures are built in from the start,” says Freije.PageBreak 

Elements of the HACCP Plan
A single document shall be produced for a complete HACCP plan. The plan shall include, at a minimum, the following eight elements:

  1. Members of the HACCP team, including their respective titles, roles, and contact information, shall be listed.
  2. Process flow diagrams for the potable water system and the utility water system. Schematically show step-wise how potable (domestic) and utility water (non-potable) are processed in the facility. Processing steps shall be named and numbered.
  3. Hazard analysis summaries shall list the name and number of each processing step in the building water system and the potential hazard(s) for each processing step. Indicate whether the team judges the risk at each step to be significant (yes or no) and briefly state the basis for that decision. List hazard control that is currently applied or could be applied to prevent, eliminate, or reduce the hazard at each control point. Critical control points (CCPs) shall be selected and indicated in the hazard analysis summaries and may also be indicated on the process flow diagrams.
  4. A monitoring schedule shall document each CCP, the frequency with which each CCP is monitored, and the timeframe in which corrective actions shall be taken when critical limits are exceeded.
  5. An equipment device maintenance procedure shall be developed for each potable or utility water device identified in the process flow diagram.
  6. A validation summary shall include the justification and, when available, scientific evidence used to validate the selection of each CCP and each critical limit selected by the HACCP team. The selection of critical limits shall comply with local guidance or regulations.
  7. A verification schedule shall list all verification activities and the frequency with which they will be performed.
  8. Planned responses to disruptions in water service shall be documented in the HACCP.

Looking Down the Road
The costs of creating a HACCP plan are relatively small compared to those of a lawsuit.

“Most preventive measures boil down to good maintenance,” Freije says. “If you have a well-maintained building, then it may not cost that much to implement a Legionella HACCP plan.”

However, preventive measures alone may not be enough to protect a building. particularly if maintenance has been lax. You may need a safeguard such as a water disinfection system.

While this investment could run upwards of $50,000 plus monthly costs, it pales in comparison to the remediation steps mandated for asbestos control or legal fees for food poisoning cases.

Anticipated to be finalized in fall 2012, Standard 188P will serve as the latest benchmark against Legionella. As a voluntary consensus standard, there is no enforcement or regulatory body that can fine an owner who fails to comply – there is no legal mandate for abiding by the standard.

“However, the power of a voluntary consensus standard and practice specification standard is that it precisely defines a technical best practice about what to do regarding a particular problem,” McCoy and Pearson add. “Because of strict and well-defined rules, the standard language is normative (mandatory) and therefore code ready.”

“We may also see this adopted by non-profit credentialing agencies in time, like USGBC,” speculates Turner. “These are the routes that standards often take to become integrated into building operations and management.”

Jennie Morton ([email protected]) is associate editor of BUILDINGS.

About the Author

Jennie Morton

A former BUILDINGS editor, Jennie Morton is a freelance writer specializing in commercial architecture, IoT and proptech.

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