Water Treatment
ASHRAE Technical Committee 3.6

Scope of TC 3.6

TC 3.6 is concerned with water treatment for building water systems including scale, corrosion and microbiological control (except sewage drainage systems) and the impacts of water treatment on building operations, maintenance, sustainability, energy efficiency, human health, and water resource conservation.


The ASHRAE Handbook is published in a series of four volumes, one of which is revised each year, ensuring that no volume is older than four years.

TC 3.6 is responsible for the following chapter in the HVAC APPLICATIONS handbook:

Water Treatment

This chapter covers the fundamentals of water treatment. It provides guidance on the treatment of water and water-based fluids used in heating, air-conditioning, refrigeration, and process systems, with a focus on the control of corrosion, scale, fouling, and biological growth. Proper treatment improves the performance and energy efficiency of these systems while helping to protect human health and safety. Water treatment also extends the life of equipment in both open- and closed-loop systems. In addition, water treatment can help conserve water resources as well as enable the use of alternative sources of water. All of these benefits help to promote a healthier, more sustainable environment.

The ASHRAE HVAC APPLICATIONS HANDBOOK may be purchased from the on-line bookstore by clicking on the highlighted text.

Comment on the Handbook: ASHRAE welcomes your comments on the Handbook or a specific Handbook chapter.  To submit a comment about any aspect or part of the Handbook series, you can use the Handbook Comment Form.

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Technical committees develop and sponsor technical sessions at the winter and annual conferences. Information about their future technical program is discussed at each TC meeting and at the TC’s Program Subcommittee meeting.

ASHRAE publishes papers and transactions from presentations at its conference events. In addition, ASHRAE records most of the seminar sessions from its conferences on DVD. These DVDs are ideal for use at chapter meetings, in university courses, or company lunch and learns. Products available from the most recent conference may be found here.

Some recent technical sessions sponsored or cosponsored by TC 3.6:


Winter Meeting 2018 in Chicago


Seminar 19 (Intermediate): 8:00 AM – 9:30 AM / Room: Chicago

“Navigating the Changing Landscape of Regulations, Codes and "Best Practices" Around Legionella and Building Water Safety” Track: Standards, Guidelines and Codes

Sponsor: 3.6 Water Treatment, Environmental Health Committee, SSPC188

Chair: Joshua Ince, P.E., Member, Eldon Water Inc, West Chester, OH

This session reviews the most current and recent codes and regulations pertaining to Legionella and building water safety, how to follow and adhere to these regulations and discuss how effective they are. The expert panel answers questions pertaining to why these regulations are required to control Legionella, strategies for executing management plans to comply with codes and regulations and discusses which codes and regulations have had the greatest impact for the management team and improving water safety.

  1. Where Legionella Lurks in Building Water Systems: How Codes and Regulations Seek to Control Amplification

Janet Stout, Ph.D., Associate Member, Special Pathogens Laboratory, Pittsburgh, PA

The aim of regulatory documents is to manage the conditions within potable and utility water systems that allow uncontrolled growth of this bacteria. This session provides you with a unique perspective – Legionella’s perspective. Understanding the water systems from this vantage point will enable owners and managers to effectively manage these systems, understand previous failures, set achievable goals and to have greater success in controlling the growth of this waterborne pathogen.

  1. Water Safety Plans, Who Does What? The Role of Water Treatment, Engineering and Facility Management

William Pearson, Member

For almost four decades, the facility manager, the engineer and the water treater were essentially without any specific or enforceable Legionella-related building water safety codes, regulations or published Standard (of care). The past two years have seen significant change, starting with the June 2015 publishing of the first US (Legionella) Standard, ANSI/ASHRAE 188, quickly followed by regulations enacted in NYC and NYS following an outbreak of Legionnaires’ disease in the South Bronx and with a June 2017 directive from CMS (Centers for Medicare and Medicaid Services) that spells out very specific Legionella-related building water safety policies and procedures requirements.

  1. Legionella: The Drive for More Effective Codes

Tim Keane, Member, Legionella Risk Management Inc., Chalfont, PA

With ASHRAE Standard 188 published and supported by CDC as well as others, CMS finally weighed in and immediately required all healthcare facilities including all hospitals and nursing homes in the US to have a Legionella risk management plan. This is a huge change from where we were just three years ago. So, what's next? What other codes will this replace, what other codes will need to change and what will be the effect on design engineers.


Winter Meeting 2017 in Las Vegas

TC 3.6 is sponsoring this technical session at the Las Vegas Conference:

Monday, January 30, 11:00 AM-12:00 PM
SEMINAR 32: Ref Cooling Water-Saturation Indices: Understanding the Water Balance When Designing and Operating a HVAC System
Chair: Dan B. Weimar, Chem-Aqua, Inc

Specifying the water usage ratio for HVAC equipment is an increasing goal in high performance building designs. This session introduces the concept of saturation indices for heat transfer systems, and demonstrate the tools available for predicting water consumption, water treatment control limits and chemical treatment directives. We will further delve into how the indices can be utilized to develop a successful water treatment program which balance water consumption and equipment life. This seminar provides the engineer, owner and operator with the tools and understanding necessary, for an efficient HVAC system, regardless of local makeup water quality.

Jeff Boldt, P.E., KJWW Engineering Consultants

Joshua Ince, P.Eng, Eldon Water Inc.



Annual Meeting 2016 in St. Louis

TC 3.6 is sponsoring two two technical sessions at the St. Louis conference:

Seminar 7: Building Water Systems: Issues and Insights from Outbreaks of Legionnaires' Disease

This session delves into understanding issues that are associated with recent and past outbreaks.  It dispels popular myths of Legionella bacteria and Legionnaires' Disease, while introducing insights to aid system designers, facility managers and public health inspectors to collectively lower the risk of Legionella amplification within building water systems.  improved understanding of this disease's root causes will allow the usage of appropriate legislation that is effective in reducing human exposure to Legionella.  The expert panel answers questions regarding lessons learned from first-hand outbreak investigation experience, issues with conflicting code requirements and actions required to minimize incidence of Legionnaires' disease.

  1. 1. Why Legionella is a Problem in Building Water Systems - Dr. Janet Stout, Special Pathogens Laboratory
  2. 2. Lessons learned from Potable Water Outbreak Investigations: Issues with Public Health and Plumbing Codes - Tim Keane, Legionella Risk Management Inc 
  3. 3. Policy Consequences of Outbreaks, Who Got it Right? - Sarah Ferrari, Evapco Inc.

Winter Meeting 2015 in Chicago
TC 3.6 is co-sponsoring with TC 8.6 and TC 5.7 Seminar 52: Alternative Sources of Recycle/Makeup Water: Practical Considerations for What SHOULD be a Good Idea
 Dwindling fresh water supplies (exacerbated by extreme drought and climate change) are bringing ever-greater pressures to utilize water conservation strategies. Increasingly, standards and codes are mandating the use of recycled water as one strategy to achieve this; another is to employ seawater for evaporative cooling systems. These strategies can be successfully utilized to relieve the stress on fresh water supplies; however, there are practical matters to consider in order to ensure that today’s good idea does not become tomorrow’s nightmare. This seminar explores some of these considerations and provides technical and valuation guidance to engineers and building owners/operators.
Chair:  Leon Shapiro, Member, Evoqua Water Technologies, Oak Park, CA

 1. Considerations in Using Recycled Water in Your Water Conservation Efforts
 Dan Weimar, Member, Chem-Aqua, Tallahassee, FL
 2. On-Site Water Reclamation for Recycled Water Conservation
 Reid Alan Spence, P.E., Member, Emcor Facilities Services, Arlington, VA
 3. Applications for Use of Reclaim Water for Evaporative Air Coolers
 Patricia Graef, P.E., Fellow ASHRAE, Munters Corporation, Fort Myers, FL

Winter Meeting 2014 in New York City
TC 3.6 co-sponsored with TC 8.6 Workshop 4:  Increasing Role of Advanced Equipment of Control and Monitoring in the Water Treatment Industry
 Chair: William E. Pearson II, Member, Southeastern Labs, Raleigh, NC

 Amazing progress has been made in remote monitoring, control, and use of technology in the water treatment industry. In this session, attendees learn how to use these tools to advance and optimize water treatment programs monitoring from your computer, tablet, or phone including iCloud applications. It's really COOL stuff.
1. The Emerging Role of Technology in Cooling Water Treatment
 Todd Cornwell, Member, Garrett Calahan Company, Raliegh, NC
2. Communicating with Other Bacnet or Other Building Management System and Cloud Storage
 Henry A. Becker, Member, H-O-H Water Technology, Inc, Palatine, IL
 3. Remote Monitoring of Water Treatment Equipment in Today’s Steam Plant
 Dan Wiemar, Member, Chem-Aqua, Tallahassee, FL


Technical Committees are responsible for identifying research topics, proposing research projects, selecting bidders, and monitoring research projects funded by ASHRAE. Information about their specific research program is discussed at each TC meeting and at the TC’s Research Subcommittee meeting.

Click here for the TC 3.6 Long Range Research Plan.


ASHRAE writes standards for the purpose of establishing consensus for: 1) methods of test for use in commerce and 2) performance criteria for use as facilitators with which to guide the industry. ASHRAE publishes the following three types of voluntary consensus standards: Method of Measurement or Test (MOT), Standard Design and Standard Practice. ASHRAE does not write rating standards unless a suitable rating standard will not otherwise be available. ASHRAE is accredited by the American National Standards Institute (ANSI) and follows ANSI's requirements for due process and standards development. Standards may be purchased at the ASHRAE Bookstore.

ASHRAE Guideline 12: Minimizing the Risk of Legionellosis Associated With Building Water Systems

ANSI/ASHRAE Standard 188: Legionellosis: Risk Management for Building Water Systems

Other Activities

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Include other activities, such as MTG involvement, into this section.


ASHRAE Technical FAQs are provided as a service to ASHRAE members, users of ASHRAE publications, and the general public. While every effort has been made to ensure their accuracy and reliability, they are advisory and provided for informational purposes only, and in many cases represent only one person’s view. They are not intended and should not be relied on as an official statement of ASHRAE. Technical questions not addressed may be submitted to the ASHRAE Technical Services department at tse@ashrae.net.

How does ASHRAE recommend that cooling towers be cleaned to avoid Legionellosis? (18)

Working Group

The following link can be used to access the TC3.6 working group: