There is still much to learn about the bacterium Legionella pneumophila and some of the other members of the genus Legionella that can cause Legionnaires' disease. But we already know for certain that parts of building water systems like cooling towers, hot tubs and hot and cold potable water systems can provide the conditions needed for the bacteria to grow or even thrive. Big populations of Legionella pneumophila that grow in inadequately managed building water systems pose an increased risk of Legionnaires' disease for the building occupants, visitors and staff. Understanding and managing this risk will take a partnership between drinking water suppliers (public water systems), building owners and operators and public health authorities.

Public Water Systems

The panels below describe the sequence of events that result in exposures to Legionella bacteria from potable water systems. Because Legionella are environmental bacteria (bacteria that can grow in the environment without hosts) and because Legionella is suited for survival in treated drinking water, studies have shown that Legionella bacteria are often present in drinking water supplies, though usually at very low numbers. As a partner in managing Legionnaires' disease risk, public water systems can treat and manage their water to reduce the likelihood that Legionella bacteria are present at high numbers, but in most cases they cannot eradicate them.

Building Owners and Building Water System Operators

If water with low numbers of Legionella bacteria get into a building water system, conditions can be much better for the bacteria to grow to numbers that make infection more likely. Water in building water systems is no longer under the control of water supplier; it is the responsibility of the building owner and (for large buildings) the staff who maintain and operate the water systems. So, building owners and water system operators are the second partners in Legionnaires' Disease risk management. There are many actions that can reduce the likelihood the Legionella bacteria grow to risky populations and the best approach for making sure the right actions are taken is to develop and implement a Water Management Program. The US Centers for Disease Control and Prevention water management program toolkit ( Toolkit: Developing a Water Management Program to Reduce Legionella Growth and Spread in Buildings ) is a good resource for developing and sustaining a water management program.

The Public Health Community

The third critical partner in Legionnaires' disease risk management is the public health community. Public health officials track Legionnaires' disease and epidemiologists research Legionnaires' disease cases and outbreaks to determine the source. The public health community also has a limited degree of oversight for water systems of health care facilities and, in some communities, has programs for managing Legionnaires' disease risk from cooling towers. Cooling towers are separate from building potable water systems and have been identfied as the source of pathogens in some large recent outbreaks.

ESPRI is a committed partner in the effort to reduce Legionnaires' disease risk. We'll update this page periodically with some activities we're working on. We hope you find them interesting and useful and invite you to email us with comments on our activities or to let us know how you're contributing to Legionnaires' disease risk management.  

Is it Time for a New Certification for Staff who Operate the Buildings with Water Systems Designated Public Water Systems?

In some states, some building water systems are regulated as public water systems (PWSs) because they meet criteria such as conducting on-site supplemental water disinfection. One of the many requirements of PWSs is that they must be operated by a certified operator. For now, the only operator certifications available are for drinking water treament operation. This seems like a mismatch, since the knowledge, skills and abilities associated with running a building water system are different from those needed to run a treatment system. That mismatch could mean too few operators available to operate building water systems or it could mean drawing certified operators away from treatment plants. The drinking water industry already has concerns about loss of skilled staff as the "grey tsunami" of retirements rolls over the industry. The mismatch in building operator certification also means that building operators do not necessarily have the knowledge, skills and abilities approporiate for effectively running a building water system.

ASDWA (The Association of State Drinking Water Authorities) asked ESPRI to write a white paper exploring whether a new certification specific to building operation is needed and, if so, what knowledge, skills and abilities would certified operators need. ESPRI's report ( ASDWA Building Operator White Paper) supports development of a new certification. Since publication of the report, Professionals in the American Water Works Association "Beyond the Meter" Premise Plumbing Subcommittee have continued to explore the need for a new certification and the process for developing the new certification. Early discussions support developing a range of operations for building operator certification inlcuding a new certification for staff operating buildings designated as PWSs, certifcate programs for other buildings and developing manuals of best practice for others.

If you have ideas about building operator certification, we'd like to hear about them. Please email us your thoughts (espri@esprinstitute.org).  

Collateral Heating and Legionnaires' Disease