Legionnaires’ disease puts plumbing in the news on a frequent basis — in the worst way.

An outbreak in Flint, Michigan exacerbated the misery of the lead crisis, killing 12 people and sickening at least 87. In Illinois, an outbreak at a VA home in Quincy cost 14 veterans their lives and the state’s VA director her job. In December, a health official identified a Disneyland cooling tower as the likely source for 22 cases of the disease. If it feels like the outbreaks are becoming more common, it’s because they are. According to the Center for Disease Control, in the United States, the rate of reported cases of Legionnaires’ disease has grown by nearly five and-a-half times since 2000.

The issue has forced the plumbing industry to reassess water safety, but the alphabet soup of government agencies, codes and standards has not abated a general level of confusion. Ask five different plumbing engineers the best way to design against legionella, and you might not be surprised to hear five different answers. Engineers looking for clarity can refer to ASHRAE 188 for managing risk in building water systems; and a recent addition to the Uniform Plumbing Code can help them right-size pipes in residential projects, though the industry is looking for similar code guidance for commercial applications.

“Whether you’re talking to a manufacturer, a facility manager at a hospital or an infection control director, I think there’s still a lot of scrambling going on because there’s no consensus of what the right thing to do is,” says Jana Summey, healthcare market manager at Watts Water. “And there probably isn’t one solution that’s going to fit every building type.”

If the solution is amorphous, a clear consensus appears to have formed upon the correlation between the beginning of Legionnaires’ disease outbreaks in 1976 and the advent of low-flow fixtures and other water-conservation efforts that achieved sustainability goals, but also reduced water velocity in piping systems designed to handle much more volume. Recognizing the issue, the EPA awarded $4 million in research grants in a funding program named 2016 National Priorities: Impacts of Water Conservation on Water Quality in Premise Plumbing and Water Distribution Systems.

That trickle of hot water in oversized pipes allows biofilm to accumulate on pipe walls, providing an ideal ecosystem for legionella bacteria to grow at deadly rates.

“The existing plumbing code has not caught up with the water use reduction, and there needs to be a very careful, scientifically- driven evaluation of, how do we balance that out?” says Chris Boyd, general manager for building water health with NSF International. “How does the plumbing design for a low-flow environment look different than the plumbing design that we’ve been using for the last 50 years?”

Better surveillance and awareness of the disease is also attributable to the rising numbers.

“Legionellosis … looks like you have pneumonia,” says Pete DeMarco, executive vice president of advocacy and research at The IAPMO Group. “And it’s a very specific test that has to be cultured and run on the sick individual to determine if that pneumonia is legionellosis. And that has not happened in the past. Even today, surveillance of attributing pneumonia to legionella is probably not as good as it needs to be.

“So we don’t know what the new numbers are, and we certainly don’t know what the numbers were before. The reality is that legionella is part of the flora of plumbing systems. And regardless of the water efficiencies — the lower flows — we need to understand how it thrives in plumbing systems and how it thrives in building water systems and how to best manage those systems to mitigate outbreaks.”

There are several efforts afoot to bring the disparate parties together to tackle the problem. In 2017, the Centers for Medicare & Medicaid Services required healthcare institutions to have a proactive water management plan for waterborne pathogens including legionella. The CDC also released a comprehensive review of outbreak investigations, and came to the conclusion from that process that 90% of the outbreaks could have been prevented with a well implemented water management plan in place.

“We’re starting to bring those people in one room,” Summey says. “In the past, you would have never heard about an infection prevention person being heavily involved with a director of engineering or a plumbing manufacturer. You’re seeing those people coming into one room and really trying to figure out how to address the challenges and come up with the best solution.”

When action is taken, it’s not guaranteed to be correct. In response to the Quincy, Illinois VA home scandal, Illinois recently proposed changes to its plumbing code. Longtime pme columnist Julius Ballanco flags the new code as misguided, and possibly dangerous, in his column this month on page 8.



Committee members from ASHRAE and NSF International, a health standards writing organization, proposed a new agreement this winter to finish the building water-management standard previously known as NSF 444: Prevention of Injury and Disease Associated with Building Water Systems. The new standard would be known as ASHRAE/NSF Standard 514 on Prevention of Injury and Disease Associated with Building Water Systems, and would take the place of 444, which was disbanded. The ASHRAE board then decided at a January meeting to table the new proposal agreement for 514 indefinitely. The draft of NSF 444 was developed by a joint committee of stakeholders that includes several ASHRAE members who were also involved in the development of ASHRAE 188, which was approved in 2015.

ASHRAE 188 focuses on legionella. Standard 444 (and ASHRAE/ NSF 514) intended to be broader, according to an NSF spokesperson, covering prevention of injury and disease from legionella as well as other waterborne pathogens, chemicals and hazards.

Turbulence in the NSF 444 committee led to the regrouping effort around 514. Several 444 members resigned this spring due to concerns over conflict of interest created when NSF International’s Water Services program signed a nonexclusive professional services agreement with building water services provider Homeyer Consulting, according to resignation letters obtained by pme.

Homeyer provides health-care facilities with hazard assessments, inspections, and/or testing to control legionella in their water systems. NSF officials defended the service agreement, stating in a press release it was between its for-profit water services program and Homeyer. The statement said it would not influence the NSF’s nonprofit Standards Development Organization. Dissatisfaction with the original 2016 memorandum of understanding between ASHRAE and ASF led to resignations from ASHRAE’s 188 committee, as well, according to former member Tim Keane.

News about the possible 514 group could be a new way forward for the joint standard, though its future is unclear, at the moment. In the meantime, ASHRAE 188 has remained one of the industry’s few lodestars for legionella. As a standard, it doesn’t require specifications in the same way as code, but for engineers, it requires them to implement a water safety system in certain situations. When followed, it can prevent against litigation, which is a growing risk.

The pending addition of Guideline 12, which is moving through the public comment period and toward possible approval by ASHRAE later this year, would provide discrete recommendations for design engineers, building owners, facility managers and those responsible for managing operating building water systems. It outlines control measures in six different areas: temperature control, disinfection or supplemental disinfection or treatment, filtration, flushing, recirculation, and cleaning and maintenance. Each then has specific action items that can be applied, according to DeMarco, who is a member of the ASHRAE 188 committee.

“Whenever there’s litigation, the plumbing engineer and the manufacturer will get sued,” says Keane, plumbing consultant, owner of Legionella Risk Management and former member of the ASHRAE 188 committee. “So they should know about ASHRAE 188. They should know about Guideline 12. They are considered industry best practices, and if they don’t know them, then they’re liable for being negligent.”

He cautions plumbing engineers need to be aware of the legionella risk posed by cooling towers, potable water systems and out-of-date aspects of the code. There are many opportunities for plumbing product technology — some new technology will have a huge impact on reducing legionella risk while some will do the exact opposite, he adds.

“They need to make sure the building owner is aware of the risk, and that they’re aware of the best practices and guidelines that they should follow to minimize the risk, and that’s ASHRAE 188 and Guideline 12,” Keane says. “In additional to issues with codes, key factors in controlling growth of waterborne pathogens, including legionella in building water systems, is building architectural design, as well as plumbing system design, operation and maintenance.”



The 2018 Uniform Plumbing Code took a major step last year when it added Appendix M: Peak Water Demand Calculator. It took data from an existing study of thousands of data points in thousands of residences, and created a sophisticated formula for engineers to right-size pipes for lower flow rates in high-efficiency dwellings. This is the first major code change reducing pipe size in more than 40 years.

“It’s a great start, we need to do something similar for commercial occupancies,” says Gary Klein, president of plumbing and energy consultant group Gary Klein and Associates “There’s no mechanism today for plumbing engineers to hang their hat on that allows them to rightsize pipes (in commercial projects). It’s a big risk because they can’t refer to a standard method or anything else.”

DeMarco said Appendix M was the result of about eight years of collaborative work between IAPMO, which develops the UPC, the American Society of Plumbing Engineers, the Water Quality Research Foundation and the University of Cincinnati.

“Arriving at a new statistically based formula for reducing pipe sizes is an extremely complex thing to do,” DeMarco says. “There are extreme risks in under-sizing plumbing systems, such as depleting the residual pressure in the plumbing system, and creating excessive flow velocities that can have negative consequences such as water hammer. And it can increase the potential for thermal shock. All those things are reasons why any reduction in pipe sizing calculations needs to be taken very carefully.”

DeMarco says IAPMO believes the new formula has potential to be applied to nonresidential building types, but that there isn’t an existing water-use database like the one they used to develop the residential formula. Eventually, when IAPMO has such data, it hopes to look at different non-residential building types and apply it. Office buildings might be first up.

“It should be easy enough to put the monitoring equipment in office buildings to be able to generate that data at a reasonable cost to be able to understand how water is being used,” he says.

DeMarco says government agencies such as the National Institute of Standards and Technologies and the EPA need to provide funding to initiate monitoring studies.

“This is a process that IAPMO has been leading for the past 8-10 years — advocating for that research to be conducted, and advising the government of its need to step up and do that work so that we can have these formulas to apply to non-residential building types,” he says. “Quite frankly, it’s a shame that we had to do it ourselves for residential. The original Hunter’s Curve was developed by the National Bureau of Standards which is now NIST, back in the 1940s. So the government stepped up and did this work because they realized it was beyond the abilities of the private sector to do it in the 1940s. The need for a new, focused public — private sector partnership to address pipe-sizing is even more profound today because of the more complex plumbing systems that we have and the threats to water safety that we are seeing.”

In addition to appendix M, Keane participated in a task force that submitted a proposal to add an N appendix to the Uniform Plumbing Code, which would create a standard language to talk about the relationship between temperature, scalding and legionella. It’s aimed to define the language so when plumbing engineers read a set of words meant to identify a certain range of temperatures in one resource, the same words refer to the same temperatures in every other resource.

“There is no standard language for the plumbing community to use,” Klein says. “This is the first time everything has been put into one table, across at least two different categories of importance for the people who use plumbing fixtures to have something in place. It would be a real big deal if that appendix gets adopted.”


Manufacturer product trends

Manufacturers approach legionella prevention with a multibarrier strategy.

“The main thing, starting in your mechanical room, you have the ability to have a water heater that is legionella resistant, basically,” Summey says. “You have the ability to have your digital mixing system that’s going to control your heat. You can put in that UV system that will kill it. You can have a scale — reduction system at the point of entry. Then, moving through the piping to the point of use, you’re going to be looking at your mixing valves, you’re doing anything else for possible stagnant water, and you’re going to be looking at point-of-use filters.”

Keeping water moving, and hot, is leading to more thermostatic balancing valves in the marketplace, explains Dave Desjardins, manager of strategic initiatives at Viega.

“When you start looking at the recirculation side of things, if it’s not balanced correctly, then you have the unintended consequences of wasting water, wasting energy, and last but not least, you could have stagnant water and a legionella issue,” he says. “So there are different balancing technologies coming out in the marketplace. Thermostatic balancing valves create a balance based off temperature. From a hot-water delivery standpoint and energy savings, you avoid standing water and reduce that risk of legionella.”

Desjardins also sees more pipe-in-pipe solutions aimed at insulating hot-water temperatures in the return pipe to create energy savings. “You don’t have that heat loss, so from saving energy or reducing energy loss, you usually look at 25-30% energy savings with that type of approach,” he says.

Back To Top