ASHRAE Standard On Legionellosis Open For Comment

A proposed standard practice that specifies requirements to prevent legionellosis associated with building water systems is currently open for public review from ASHRAE. The ASHRAE Standard 188P, Prevention of Legionellosis Associated with Building Water Systems, is intended to address the “what” of controlling the spread of legionellosis. The standard helps facility managers/owners understand how to apply the available information on Legionella effectively in order to prevent cases of legionellosis associated with building water systems.

The bacterium Legionella can lead to a very serious form of pneumonia, referred to as Legionnaires’ disease, or Pontiac fever, which is a less severe form of the disease. There are many thousands of cases every year in the U.S. Essentially all cases of legionellosis are the result of exposure to Legionella associated with building water systems.

Read TFM‘s June 2011 coverage of Standard 188P in “The HVAC Factor” column here.

“We know how to analyze and control this hazard,” Bill McCoy, chair of the Standard 188P committee, said. “We need a standardized practice to specify for facility managers/owners exactly what to do in their facilities to control the hazard in a systematic and scientifically defensible way.”

The proposed standard underwent an earlier public review in November 2010 and is currently open for a second public review until July 25. Since the standard’s first public review, Section 8.1 on potable water has been rewritten. Originally, the section included several system design specifications; however, those design oriented specifications were eliminated because Standard 188P is intended to be a practices standard, rather than a design standard. The newly revised Section 8 clarifies this aspect.

Compliance with the standard requires facility managers/owners to formally take responsibility for controlling Legionella in their building water systems, while at the same time acts as a defense against accusations of negligence in those cases which are caused by the hazard from unknown sources.

Standard 188P also covers the potable water system in buildings, which are not treated as often as cooling towers, and will hold facility managers/owners accountable for properly managing the entire building water system both potable and utility water.

The standard differs from ASHRAE Guideline 12, Minimizing the Risk of Legionellosis Associated with Building Water Systems, in that while the guideline gives recommendations about how to treat various building water systems, the standard specifies the practice of exactly what must be done with all those recommendations. “The standard and the guideline are, therefore, complementary,” McCoy said.


  1. I’ve been carrying on a 1-man fight, over the past several years, to alert the public to the dangers of Legionnaires’ Disease. I’m a mechanical engineer/environmentalist, who opposes the “experts” recommending dialing down H2O heaters to 120 degF to save energy (but introducing the possibility of fostering the virus). As you undoubtedly know, any H2O system kept below 140 degF where possible stagnation and sedimentation exists, is a potential breeding ground. Recently, there was an outbreak at the Playboy Mansion in LA; also a hotel in GB. 2 years ago in the Chicagoland Area, there were 2 who died in a Retirement Home (these & Nursing Homes dial down hot H20 temps to prevent scalding) and 1 electrician who was working on a Chicago Transit Authority bus wash. I’ve written to Natl. Geographic, AARP, Popular Mechanics, etc., to no avail. There’s a small group, like me, who’re trying to develop a website to reach the populace. Certainly, with ASHRAE at the forefront, lives can be saved! I’m available for any further support needed, and greatly appreciate your efforts in this direction.

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