Water: Life’s Vital Necessity Can Also Be a Pool for Pathogens

Infection Control Today, Volume 26, Issue 3

How do you protect against waterborne infections when water itself is nearly ubiquitous?

The water left in the shower drain. Dialysis water. Flower vases. That decorative waterfall in the lobby. The ice machine.

Water, water everywhere—and so easily turned into a pool for pathogens.

Reservoirs, meaning any place indoors or out where water can accumulate, in all sorts of places, expected and unexpected, are linked to nosocomial outbreaks of infections. Investigators from the University of North Carolina, for instance, tallied a multitude when they reviewed 1746 reports of health care­–associated outbreaks and infections linked to a water reservoir.

The reports varied widely in both origins of contamination and results. In one case, whirlpool tub water was contaminated from the drain when the tub was filled, leading to “strong causation” of bloodstream infection, pneumonia, and urinary tract infection in patients with leukemia. At another facility, an outbreak of Pseudomonas aeruginosa in the intensive care unit was traced to contaminated faucets. In another instance, patients developed postoperative wound infections after ice contaminated with Enterobacter cloacae was used for cardioplegia. In a nursing home, patients who inhaled shower aerosols developed Pontiac fever.

Water-damaged plaster caused an outbreak of Mucor. Deionized water from a hospital pharmacy caused an outbreak of Exophiala jeanselmei. A miscellany of nontuberculous Mycobacteriumcaused nosocomial outbreaks: Mycobacterium abscessus in tap water, Mycobacterium avium in potable water, Mycobacterium chelonae in ice and ice machines, Mycobacterium chimaera in heater-cooler units, Mycobacterium fortuitum in hospital showers…the list goes on.1

Because the issue often is the entire water system, everyone in the hospital is at risk all the time. The enemy is always at the gates. According to a 2019 presentation at an Association for Professionals in Infection Control and Epidemiology (APIC) Greater NY chapter meeting, for instance, 70% of all building water systems contain Legionella.2

Think of all the ways water is used in a hospital. How do you protect against waterborne infections when water itself is nearly ubiquitous?

The first step for a health care facility is to develop or improve a water management program.“They should first ensure that they have a water management program team, a multidisciplinary group including representation from facility administration, facilities management, facilities engineering, and infection prevention, with other team members included depending upon expertise and needed roles,” Kiran Mayi Perkins, MD, medical officer and team lead, Outbreak and Response Team, CDC, told Infection Control Today® (the CDC has a Healthcare Facility Water Management Program Checklist to help health care facilities develop a program3).

Having a team is important, but Kari Brisolara, ScD, MSPH, associate professor of environmental and occupational health sciences at Louisiana State University’s School of Public Health in New Orleans, told Infection Control Today® that “one aspect that tends to have the most impact but tends to be lacking from the priority list is the importance of managerial buy-in. The ideas of proactive vs reactive managerial styles and how education and outreach programs are prioritized by upper and midlevel management within a facility are just as important as the engineering design in some cases.”

Once the team is pulled together, the process is multistep: Members need to describe the building water systems using flow diagrams and a written description to identify areas where Legionella and other opportunistic premise plumbing pathogens (OPPPs) could grow and spread. Thereafter, the steps are programmatic: Decide where control measures should be applied and how to monitor them, establish ways to intervene when control limits are not met, make sure the program is running as designed and is effective, and document and communicate all activities.

What are some areas most likely to be overlooked? Rasha Maal-Bared, a wastewater treatment specialist at EPCOR, a utility company in Edmonton, Alberta, Canada, gives some pointers, with particular reference to Legionella:

  1. Maintain water temperatures outside the ideal range for Legionella growth (77-113 °F). According to APIC, Legionella can live and proliferate in a facility’s water system at a wide range of temperatures: from below 68 °F, at which the pathogen survives but is dormant, to 151 °F, at which 99% of the pathogen dies within 2 minutes of direct contact.
  2. Identify areas in the facility where aerosolization and cross-contamination are likely.
  3. Prevent water stagnation, especially in medical and dental devices.
  4. Maintain premise plumbing, equipment, and fixtures to prevent sediment, scale, corrosion, and biofilm, all of which nurture pathogens. (Maal-Bared notes that the ASHRAE 188 standard does not require building managers to test for Legionella, given the lack of scientific consensus on the topic. Teams that do decide to test for Legionella must have a clear idea of sampling methods, tests, sites, and frequency ahead of time; and what corrective actions will be taken should Legionella be detected in the water system.)

Maal-Bared adds an important recommendation: Develop “a robust relationship” with the utility in the jurisdiction to get notifications of changes in water quality due to main breaks, infrastructure repair, construction, or depressurizations.

Perkins points out another area of clinical care that may often be overlooked:respiratory therapy. “Many outbreaks due to water-related organisms have involved respiratory infections,” she says. “Providing respiratory therapy may involve potential routes of transmission of water-related organisms, for instance via nebulized products and respiratory equipment that uses water, either intentionally or inadvertently.”

Tracking Down the Pathogens

Every day about 1 in 31 US hospital patients receives a diagnosis of at least 1 infection related to hospital care alone.4 The cause of many of those? Water. An estimated 65% of health care–acquired infections (HAIs) are associated with wet biofilms or the presence of moisture or liquid.5

It is not always easy to pinpoint the culprit. Investigators from University Hospital of Montpellier in France assessed the spread of OPPPs through secondary water routes (outside the plumbing system) in an adult hematology unit. They identified 6 secondary routes. P aeruginosa and Stenotrophomonas maltophilia, as well as nonpathogenic OPPP indicators, were detected in water collected upstream of antimicrobial filters. P aeruginosa was the sole OPPP retrieved from tested surfaces; the same clone of P aeruginosa spread from water source to dry surfaces in the same room and cross-contaminated 2 sinks in different rooms. Three clones of nonpathogenic OPPP indicators spread more widely in different rooms.6

Perkins says that because of the complexity of HAI outbreaks,“most investigations of water-related infection outbreaks do not identify a definitive source of infection. For this reason, it’s difficult to rank the sources of health care outbreaks involving water-related organisms. However, anecdotally and based on CDC experience in supporting health departments and health care facilities with such investigations, we have found that preparing medications and storing or placing patient care items near water sources, such as the splash zones of sinks, are often identified as potential sources of infections.”

The most common uses of water in health care facilities are typically related to domestic and restroom (about 35%) and cooling and heating (about 20%), says Brisolara. “But it’s important to examine all variations of use within the health care setting to look for risks and opportunities for minimizing use and vulnerabilities,” she continued. These include, for instance, ensuring that the water entering the facility meets all applicable quality standards; that the plumbing within the facility is designed and maintained with the goal of minimizing growth and spread of waterborne pathogens from both the supply and waste transport sides; and that exposure to potentially contaminated water sources is minimized.

It is also crucial to be on the lookout for pathogens not typically considered waterborne but that turn up in the water, say investigators from Flinders University in Adelaide, South Australia.7 They reviewed studies that investigated the role of water and water-related devices in the transmission of antimicrobial-resistant bacteria. Biofilms were a “hot spot,” they found, for disseminating genes responsible for survival functions. (Also, because different types of bacteria may contaminate the same drain, antibiotic-resistant genes may be transferred between bacterial species.)8 Staphylococcus aureus, Moraxella spp., and Enterobacter aerogenes were common in the potable water supply and on plumbing surfaces, such as faucets. Antibiotic-resistant pathogens, including extended-spectrum β-lactamase–producing Enterobacteriaceae and methicillin-resistant S aureus, were located in a hospital sink bowl, hospital bathroom sink taps, and a hospital bathtub. Faucet spouts were more contaminated than sink bowls and drains. The researchers also point to “flawed sink design,” such as shallow bowls that make it easy to splash contaminated sink contents onto patient care items, hands, and the broader environment.

A Wider Perspective

Hospitals may seem like worlds unto themselves, but they are also working parts of a larger, complex, interconnected system. In an article on monitoring coliphages, Brisolara and Maal-Bared discuss a “One Water” concept: managing all water in an integrated, inclusive, and sustainable manner.9 This posits that components of the water system have “overlapping and interactive impacts” on other aspects of the system. Such inclusiveness can have a major impact on public health and hospital populations: For instance, monitoring wastewater in communities for fecal bacterial pathogens has provided evidence of COVID-19 clusters—information that can help health officials assess spread.

Individual states develop their own water quality standards, but state rules must be at least as strict as the federal rules (ie, the federal rules represent the minimum standards). Some states choose to just follow the federal regulations, Brisolara says, but most opt for more stringent rules, usually based upon special environmental situations such as water usage restrictions and wetland protections. She adds that hospital wastewater has industry-specific effluent guidelines that facilities must meet prior to discharge into the public wastewater system.

The One Water framework emphasizes the need for multisector coordination and collaboration. Prevention of waterborne infectious diseases requires a comprehensive response because the water cycle encompasses surface and groundwater, drinking water, wastewater, stormwater, and reused or reclaimed water. The overall concept may seem simplistic, Brisolara concedes, but she says there are aspects that can be complex, including the dependency of the kinetics on climate, season, and geography.

“It allows us to look at the full picture,” Maal-Bared says. “Particularly where the pathogens are coming from. It allows us to look outside the boundaries of one building or facility and explore external changes in the distribution system or source water that will introduce hazards that require control.”

For example, although municipalities treat their water with disinfectants, several factors may help propel pathogens into a building’s water distribution system. Maal-Bared gives some examples:

  • Construction (including renovations and installation of new equipment) can cause vibrations and changes in water pressure that dislodge biofilm and release Legionella or other waterborne pathogens. Biofilm in pipes can give pathogens a safe harbor from disinfectants.
  • Water main breaks: Changes in water pressure can dislodge biofilm and release waterborne pathogens, as well as introduce dirt and other materials into the water that use up all the available disinfectant.
  • Changes in municipal water quality can increase sediment, lower disinfectant levels, increase turbidity, or cause pH to be outside recommended ranges. Also, if a supplier changes the type of disinfectant it uses, this change can impact how the water management program team should monitor its building water systems.

Taking a holistic approach comes naturally to many in health care, and it can make a difference in everything from building the water management team to teaching staff how to reduce risks in the patient’s room. “In health care, the importance of ‘One Health’ and ‘One Water’ is clear,” says Brisolara. She highlights the value of an interdisciplinary, interprofessional team. “The team is not just defined within the discipline of health care, but should include public health, engineering, water resources, environmental justice, social services, and most importantly, the community served. This is the only way to create sustainable solutions that will allow for the holistic approach to work.”

Keeping patients and staff safe from flotillas of pathogens is a daunting mandate. Perkins, Brisolara, and Maal-Bared all offer their top advice for hospitals and facilities.

“Health care facilities should remain vigilant in keeping these organisms from reaching patients through effective and strong infection prevention and control practices,” Perkins says. “They should also ensure that they’re ready to respond to signals of patient harm due to potential water-related organisms.” Moreover, health care facilities should bear in mind that it is not just about Legionella, she warns. Water management programs should address the many other organisms that inhabit health care water systems and pose a risk to patients.

Brisolara, proponent of the holistic One Water concept, says, “Think outside of your facility and comfort zone when forming a team to plan and evaluate your water.”

For Maal-Bared, it is basic: “Never underestimate the power of a good, well-thought-out water safety plan.”


  1. Kanamori H, Weber DJ, Rutala WA. Healthcare outbreaks associated with a water reservoir and infection prevention strategies. Clin Infect Dis. 2016;62(11):1423-1435. doi:10.1093/cid/ciw122
  2. Erspamer, R. Liquitech. Waterborne Pathogens: Where They Come From, Why they Matter, & Paradigms to Protect Your Facility. Association for Professionals in Infection Control and Epidemiology Greater NY Chapter 13 Meeting; May 15, 2019; New York, NY. http://apicnyc.org/2019-meetings-and-programs.html
  3. Healthcare facility water management program checklist. CDC. Updated November 17, 2021. Accessed February 15, 2022. https://www.cdc.gov/HAI/pdfs/Water-Management-Checklist-P.pdf
  4. Healthcare-associated infections (HAIs): HAI data. CDC. Updated October 5, 2018. Accessed February 15, 2022. www.cdc.gov/hai/data/index.html
  5. Yiek WK, Coenen O, Nillesen M, van Ingen J, Bowles E, Tostmann A. Outbreaks of healthcare-associated infections linked to water-containing hospital equipment: a literature review. Antimicrob Resist Infect Control. 2021;10(1):77. doi:10.1186/s13756-021-00935-6
  6. Baranovsky S, Jumas-Bilak E, Lotthé A, et al. Tracking the spread routes of opportunistic premise plumbing pathogens in a haematology unit with water points-of-use protected by antimicrobial filters. J Hosp Infect. 2018;98(1):53-59. doi:10.1016/j.jhin.2017.07.028
  7. Hayward C, Ross KE, Brown MH, Whiley H. Water as a source of antimicrobial resistance and healthcare-associated infections. Pathogens. 2020;9(8):667. doi:10.3390/pathogens9080667
  8. Healthcare-associated infections (HAIs): reduce risk from water. CDC. Updated September 11, 2019. Accessed February 15, 2022. https://www.cdc.gov/hai/prevent/environment/water.html
  9. Fitzmorris-Brisolara K, Maal-Bared R, Worley-Morse T, Danley-Thomson A, Sobsey M. Monitoring coliphages to reduce waterborne infectious disease transmission in the One Water framework. Int J Hyg Environ Health. 2022;240:113921. doi:10.1016/j.ijheh.2022.113921