TECHNICAL FEATUREThis article was published in ASHRAE Journal, October 2015. Copyright 2015 ASHRAE. Posted at This article may not be copied and/ordistributed electronically or in paper form without permission of ASHRAE. For more information about ASHRAE Journal, visit ManagementFor LegionellosisBY PAUL LINDAHL, MEMBER ASHRAE; BILL PEARSON, MEMBER ASHRAE; R. LEE MILLIES, P.E., MEMBER ASHRAEANSI/ASHRAE Standard 188, Legionellosis: Risk Management for Building Water Systems, waspublished in June. This long-awaited document establishes minimum legionellosisrisk management requirements for building water systems. The standard establishesparticular requirements for design engineers when they are involved in new buildings, renovations, additions or modifications to existing buildings.The design engineer first needs to evaluate whichrequirements of the standard apply to their project. Thisevaluation determines if the project contains any of thefollowing building risk factors: Multiple housing units with one or more centralizedhot water systems; Contains more than 10 stories (including levelsbelow grade); Health-care facility with patient stays over 24 hours; Facilities that house or treat immune-compromised, at-risk occupants such as those being treated forburns, organ transplant, chemotherapy, chronic lungdisease, diabetes; and Facilities designated for housing occupants over age65.If any of these factors are present, then the designengineer needs to comply with Section 8 requirementsin the standard with regard to potable water, both forhot and cold water systems.The evaluation also determines if the project containsone or more of the following system components: Cooling towers or evaporative condensers; Whirlpools, spas, ornamental fountains; Humidifiers, air washers, atomizers, misters; and Other nonpotable water systems or devices thathave the potential to release water aerosols, such as icemachines.If any of these system components are present, thenthe engineer needs to comply with the relevant portions of Section 8 of the standard for those systemcomponents in addition to any potable water systemrequirements necessary as a result of building risk factors in the list above. Section 8 is discussed later in thisarticle.Paul Lindahl is director of market development at SPX Thermal Equipment & Services. He is vice chair of ASHRAE SSPC 188. Bill Pearson is vice president of consulting andtechnical services at Southeastern Laboratories, Inc., a member of SSPC 188, and Association of Water Technologies liaison to ASHRAE. R. Lee Millies, P.E., is president at MilliesEngineering Group and is a member of SSPC 188.14ASHRAE JOURNALashrae.orgO CT O B E R 2 0 1 5

TECHNICAL FEATUREStandard 188 applies also to the construction andoperation phases of a project, as well as to operation andmaintenance of existing buildings.Background on the StandardThe term “legionellosis” refers to two illnesses, eachcontracted from exposure to Legionella bacteria. Themore severe form, when pneumonia results, is calledLegionnaires’ disease (LD). An estimate by the U.S.Centers for Disease Control is 8,000 to 18,000 cases ofLD per year in the United States, with more than 10% ofthose cases becoming fatal. It is important that requirements be in place to manage risk of exposure to thesebacteria from building water systems, where a significant percentage of the exposures occur. A less-severeillness known as Pontiac Fever, which has flu-like symptoms, can also be caused by Legionella.The risk of disease or illness from exposure to Legionellabacteria is not as simple as the bacteria being present ina water system. Other factors that contribute to the riskare environmental conditions that promote the growthand amplification of the bacteria in the system, a meansof transmitting this bacteria (via water aerosols generatedby the system), and the ultimate exposure of susceptiblepersons to the colonized water that is inhaled or aspiratedby the host providing a pathway to the lungs. The bacteriaare not transmitted person-to-person, or from normalingestion of water. Susceptible persons at high risk forlegionellosis include, among others, the elderly, dialysispatients, persons who smoke, and persons with medicalconditions that weaken the immune system.The development of the standard spanned over a 10year period, beginning in 2005, and published June 26,2015. Figure 1 shows a timeline of the development ofStandard 188-2015. In the course of that time, a balancedcommittee of experts produced five public review drafts,responding to comments and improving the documentat each step. With the final version, a consensus processstandard for legionellosis risk management of buildingwater systems was produced. The document is writtenin code language, so that it can be adopted as desired bygovernment bodies (see “NYC Responds to Outbreak”sidebar). ASHRAE standards are otherwise voluntary.What’s in the Standard?Standard 188 is intended for use by owners and managers of human-occupied buildings, and those involvedNYC Responds to OutbreakIn August, investigators discovered that a coolingtower at the Opera House Hotel in New York City wasthe source of a nearly monthlong outbreak of Legionnaires’ disease that caused 12 deaths and more than 120cases of infection due to Legionellosis.During the search for the source, 14 other cooling towers were found to be infected at other building sites. Nocity records were kept that indicated which buildingshave cooling towers.In response to the outbreak, the New York City Council adopted legislation that requires adherence to partof ANSI/ASHRAE Standard 188-2015, Legionellosis: RiskManagement for Building Water Systems.New York City is considered the first major U.S. city toregulate cooling towers. The legislation addresses registration and inspection of cooling towers. It requiresowners to create and file a plan to maintain equipmentto comply with Sections 5, 6 and 7.2 of the standard.Section 5 deals with building surveying, Section 6 withgeneral requirements, while Section 7.2 lists commontasks and steps for items such as new system start-upand seasonal shutdowns, general system maintenance,water treatment, disinfection plans, etc.Michael Patton, a member of the committee whowrote the standard, testified before the Council onbehalf of ASHRAE. While Patton encouraged full adoption of the standard, he said it was helpful that at leastthose sections were included.“Those sections by themselves are very good,” Pattontestified, “but it doesn’t really address the whole idea ofinforming building owners, managers, property managers how to put a plan for a whole building into placeand what it should contain.”Sources: ASHRAE, NBCNewYork.comin the design, construction, installation, commissioning, operation, maintenance and service of centralizedbuilding water systems and components.The standard specifies minimum legionellosis riskmanagement requirements for human-occupied buildings, not including residential, and their associatedpotable and nonpotable water systems.Specific compliance pathways are defined in the standard for the following groups: building designers, building owners, and health-care facilities.O CT O B E R 2 0 1 5ashrae.orgASHRAE JOURNAL15

TECHNICAL FEATUREThe compliance pathways direct each user group toa building survey (and frequency of repeated surveys),and to appropriate general and building water systemspecific requirements in the standard. The building survey evaluates the presence of certain potential aerosolgenerators and certain risk factors that relate to legionellosis. The results of the survey determine the compliance pathway that must be followed for that group andthat particular building.General requirements include establishment by building owners of a program team of one or more individuals and (in turn) a water management program forwhich they are responsible to comply with the standard.The water management program must meet specificand detailed requirements for what legionellosis controlstrategies must accomplish and how they are to be documented—but not what specific strategies are to be usedor applied. Table 1 describes the elements of the process.Please refer to the standard for specifics, but note thatbuildings that meet the criteria as to risk factors relatedto legionellosis are required to develop a plan thatFIGURE 1   Standard 188-2015 development.SPC-188 Began MeetingOctober 2010Draft 2 Released ( PR/2)February 2005*Draft 1 Released ( PR/1)ANSI/ASHRAE Standard 188-2015Legionellosis:Risk Management forBuilding Water SystemsApproved by the ASHRAE Standards Committee on May 27, 2015; by the ASHRAE Board of Directors on June 4, 2015; andby the American National Standards Institute on June 26, 2015.June 2011This Standard is under continuous maintenance by a Standing Standard Project Committee (SSPC) for which the StandardsCommittee has established a documented program for regular publication of addenda or revisions, including procedures fortimely, documented, consensus action on requests for change to any part of the Standard. The change submittal form,instructions, and deadlines may be obtained in electronic form from the ASHRAE website ( or in paperform from the Senior Manager of Standards. The latest edition of an ASHRAE Standard may be purchased from theASHRAE website ( or from ASHRAE Customer Service, 1791 Tullie Circle, NE, Atlanta, GA 30329-2305.E-mail: [email protected] Fax: 678-539-2129. Telephone: 404-636-8400 (worldwide), or toll free 1-800-527-4723 (fororders in US and Canada). For reprint permission, go to 2015 ASHRAEJanuary 2013Draft 4 Released ( PR/4)March 2015Approved by ASHRAE BoardJune 26, 2015ISSN 1041-2336Draft 3 Released ( PR/3)September 2014Draft 5 Released ( PR/5)June 4, 2015Finalized Standard 188-2015*First meeting was as GPC-12 (Guideline), later became SPC-188PR Public reviews (required by the ANSI/ASHRAE standards process)includes potable water in addition to any of the listedpotential aerosol generators that are present. If none ofthe risk factors are present, then the plan must includeonly the potential aerosol generators that are present.)RIVK] )J½GMIRX ,IEXMRK :IRXMPEXMRK .YWX SX )EWMIV 8S 7TIGMJ] With HTHV heating technology, one piece of equipment candramatically reduce energy costs and improve Indoor Air Qualityat the same time it is heating commercial and industrial buildings.To learn more about HTHV technology,SCHEDULE A LUNCH & LEARN 33-1916ASHRAE JOURNALashrae.orgO CT O B E R 2 0 1 5

TABLE 1 Elements of a water management program.PROGRAM TEAM Identify persons responsible for program development andimplementation.DESCRIBE WATER SYSTEMS/FLOW DIAGRAMS Describe the potable and nonpotablewater systems within the building and on the building site and developwater system schematics.ANALYSIS OF BUILDING WATER SYSTEMS Evaluate where hazardous conditionsmay occur in the water systems and determine where control measurescan be applied.CONTROL MEASURES Determine locations where control measures must beapplied and maintained in order to stay within established control limits.MONITORING/CORRECTIVE ACTIONS Establish procedures for monitoring whethercontrol measures are operating within established limits and, if not, takecorrective actions.CORRECTIVE ACTIONS/CONFIRMATION Establish procedures to confirm that: The program is being implemented as designed (verification). The program effectively controls the hazardous conditions throughout thebuilding water systems (validation).DOCUMENTATION Establish documentation and communication procedures forall activities of the program.In addition to the general requirements for development of the water management program, specificpreventive measure requirements for the followingbuilding water systems are required as indicatedabove: Potable water systems (when risk factors werefound in the survey). Requirements include systemstart-up and shutdown, system maintenance, watertreatments, and contingency response plans. Open and closed circuit cooling towers andevaporative condensers. Requirements include equipment siting, new system startup, system maintenance,water treatment, shutdown and start-up, disinfection,location of makeup valves, and contingency responseplans. Whirlpool spas. Requirements include batherrelated requirements, filter operation and maintenance,water quality, disinfection and monitoring, microbiology, microbiological testing (when contamination isdiscovered), contingency response plan and operatingmanuals. Ornamental fountains and other water features.Requirements include equipment siting, operation,maintenance, water treatment, and contingency response plans. Aerosol-generating misters, atomizers, air washers, and humidifiers. Requirements include equipmentsiting, new system start-up, system maintenance, JOURNALashrae.orgO CT O B E R 2 0 1 5

TECHNICAL FEATUREtreatment, system shutdown and start-up, disinfectionand contingency response plans.Requirements are included in Section 8 of the standard for designing building water systems for newconstruction, renovations, refurbishment, replacement, or repurposing of a facility. Examples of systemelements to be considered during the design processinclude: Providing proper access to expansion tanks, waterhammer arrestors, water storage tanks, pump, waterheaters and other equipment and components containing water. Maintaining proper system water temperatures andthe use of system versus point-of-service tempering valves. Providing proper insulation to control the heat lossor heat gain in water piping and system components. Provide proper protection to prevent cross connections between potable and nonpotable water systems. Design piping systems to avoid no-flow and lowflow conditions. Locate building outdoor intakes such that they JOURNALashrae.orgO CT O B E R 2 0 1 5not take in the discharge of cooling towers or evaporative condensers. Locate water system valving such that all systemscan be properly balanced.The design engineer shall also prepare constructionand as-built documents that indicate: An overview of the system and its intended mode ofoperation. A diagram of water systems including pipe routingsizes, flow rates, valving, design temperatures, temperature monitoring points, fill provisions, blowdownprovisions, makeup provisions, sampling points anddrain provisions. Locations of all equipment associated with thewater systems including equipment sizes, capacity andspecifications. Applicable water system control schematics andcomponents. Specifications for all water system components suchas piping, insulation, valves, pumps, equipment including all installation and start-up

TECHNICAL FEATUREThe design engineer also provides instructions for theproper balancing and commissioning of all buildingwater systems including the procedures for flushing anddisinfection.A normative annex with requirements for health-carefacilities is a part of the Standard. Normative Annex Aincludes requirements for health-care facilities thatmeet certain criteria as to facility accreditation and staffwho are certified as infection preventionists or with aminimum of a graduate degree in epidemiology. Theannex is written using terminology consistent with thatused in the health-care industry. The intent of the annexis to be equal to or more stringent than the base document. Health-care facilities that do not meet the criteriato use the annex must follow the base document. Pleaserefer to the standard for details.Standard 188 consists of normative sections followedby normative and informative annexes. The normative sections and normative annex specify the requirements for compliance. Building water systems can varysignificantly in their design, and in the potential of Legionella, as well as the presence of susceptible individuals. Scientific evidence is not availableor is inconclusive regarding some aspects of Legionellacontrol. The informative annexes and references provide suggestions, recommendations and references forguidance to develop water management plans for specific buildings.Next StepsThe standard is now published and converted to continuous maintenance status by ASHRAE. The strong positive response to the document has been encouraging,and ASHRAE looks forward to ongoing improvementof the document using the continuous maintenanceprocess.ANSI/ASHRAE Standard 188-2015, Legionellosis: RiskManagement for Building Water Systems, is available from theASHRAE Bookstore (, orit can be read for free online via this page,, under the Preview ASHRAE Standards section near the bottom CT O B E R 2 0 1 5ashrae.orgASHRAE JOURNAL23

tower at the Opera House Hotel in New York City was . During the search for the source, 14 other cooling tow-ers were found to be infected at other building sites. No city records were kept that indicated which buildings have cooling towers. . by the American National Standards Institute on June 26, 2015.