When ASHRAE published the first edition of Standard 188, Legionellosis: Risk Management for Building Water Systems, there was a question of: “What about other pathogens? Why concentrate on Legionella?”

In defense of ASHRAE, the reason ASHRAE 188 only addressed Legionella is because that is the scope of the standard. ASHRAE 188 has been largely ignored by the plumbing profession. Every attempt to reference the standard directly into the plumbing codes has not been successful.

The first reference to ASHRAE 188 may have occurred at the end of September at the IAPMO annual conference. ASHRAE 188 is directly referenced in the proposed new appendix to the Uniform Plumbing Code. It would be up to a local jurisdiction to adopt the new appendix. Hence, the standard still is not universally accepted in the plumbing code.

NSF saw the void and decided to create a new standard that dealt with every possible pathogen in the potable water supply, including Legionella. At first, this seemed to annoy some of the crowd from the ASHRAE school of thought. Why develop another Legionella standard for drinking water?

Things seemed to calm down when NSF indicated it would directly reference ASHRAE 188. NSF also invited ASHRAE and its membership to participate in the development of the new standard, which NSF tentatively identified as NSF 444.

NSF appeared to be the perfect organization for developing this standard. NSF had more than 30 years of experience with NSF 60 and 61. Hence, it knows a lot about drinking water. However, NSF 60 and 61 rely on the US EPA drinking water requirements. That is the basis for evaluating products for their contribution to drinking water.

A standard for reducing the presence of pathogens, including Legionella, would require NSF to ignore the EPA requirements. If you follow the EPA drinking water requirements, which are federal law, you cannot have any pathogens that can do harm in drinking water. That would include Legionella.

To develop a new standard would require acknowledging that the water utility is not meeting the federal requirements for drinking water. This is difficult to comprehend since the vast majority of water utilities are supplying water that complies with EPA requirements. If they do, how can these pathogens, including Legionella, get into the water supply?

If the water utility supplies water meeting federal law, the engineering community has asked, “Why even bother with ASHRAE 188?” The water will remain safe and we can continue to design plumbing systems the way we always have. Of course, cooling towers in HVAC systems are excluded since you never know how the Legionella may enter the water in a cooling tower. But for plumbing systems, status quo.

Many of the experts serving on the Legionella committee believe that you never know when Legionella may appear in your water. They claim that Legionella can hide from detection and then rear its ugly head. Once it does, it will grow on a biofilm and cause harm.


Secondary treatment

When it comes to secondary treatment, do you add it if there has never been any detection of pathogens in the drinking water? Or do you install water treatment, just in case?

The water treatment for a building can also create a problem for the building owners. In some states, a water treatment system may be required to be registered and the people operating it licensed as water treatment specialists. This adds a significant cost to the building owner that never goes away.

As for the plumbing design, the Legionella committee thought process is that the system should always be designed to prevent the creation of biofilms on the inside of the piping and components. That is easier said than done.

Biofilms have existed on the inside of potable water piping systems since the beginning of time. As one expert described it, biofilm is that stuff that is on your teeth in the morning before you brush them. I like that description since everyone can relate.

If there is no biofilm, the belief is that there can be no growth of a pathogen. While that sounds good for Legionella, it is not true for every pathogen. After Hurricane Katrina, the New Orleans water utility had some outbreaks of naegleria filaria. You only need one cell to enter your nose, move through the nasal canal to your brain and have it eat your brain. You are dead in a matter of days. In this case, there is no biofilm needed for the pathogen to be deadly. How do you prevent this from occurring?

After months of trying, NSF decided to transition its standard to ASHRAE. NSF 444 thus moved to ASHRAE to become ASHRAE 514. A new committee was created by ASHRAE to develop the standard for all pathogens in water, again including Legionella.

The question that ASHRAE has to deal with is does it use the draft of NSF 444 or the current edition of ASHRAE 188 as the base document? Does ASHRAE further attempt to regulate plumbing design? When analyzing ASHRAE 188, one of the concerns is the flow-through requirements, the removal of unused or rarely used water lines and the possible raising of temperatures of the hot-water distribution system. Before you get too excited, nothing is mandated, the standard provides guidelines for managing the risk of Legionellosis.

Questions regarding the age of water (how long it sits in the pipe), the use of a fixture and the timing between flushing are all parts of ASHRAE 188. Dead legs in a piping system are considered a big concern. Yet, what happens when snowbirds go south for the winter, a school shuts down for the summer or a plant closes for the holidays. These are all issues that are brought to the Legionella committee. A common response is, you assess the risk.

ASHRAE has its hands full trying to develop the new Standard 514 on pathogens in building water systems. The agreement with NSF requires ASHRAE to have a draft submitted for public review within three years. That means ASHRAE has to follow a very aggressive schedule. Those of us who have been involved with ASHRAE know its schedule is never rushed when it comes to standard development. However, this time, ASHRAE has no choice. Fortunately for ASHRAE, it already has a lot of expertise on the SSPC 188, the committee responsible for ASHRAE 188.


Editor’s note: Following this article, Julius was appointed as a non-voting member of ASHRAE SPC 514.