Reduce Risk from Water

From Plumbing to Patients

Water is the foundation of life; because of that, wet environments pose a particular hazard of infection, promoting microbial growth and serving as a source for antibiotic resistant pathogens, and healthcare-associated infections.

Tap water meets stringent safety standards in the United States, but it is not sterile. Certain numbers and types of bacteria and other microbes may be present when water leaves the tap. For typical household uses such as washing, bathing, drinking and food preparation, these microbes rarely pose a serious health risk.

In contrast, in healthcare settings, the ways we use water are more varied and patients might be more vulnerable to infection. Certain conditions within healthcare plumbing systems can even encourage microbial growth. This can lead to dangerously high levels of potential pathogens. Moreover, the risk does not stop at the tap—every use of water in patient care settings must be scrutinized and evaluated for its risk to harbor and transmit healthcare-associated pathogens. Even hospital sink drains and toilets can pose a risk for harboring antibiotic resistant pathogens that can spread to patients and cause harm.

Water Management Program

Water can harbor germs that threaten the safety of patients and spread antibiotic resistant pathogens or healthcare-associated infections (HAIs). Water management programs in healthcare facilities are an important way to help protect vulnerable patient populations as well as staff and visitors.

Patient safety depends on assuring that:

  • Water entering a healthcare facility meets all applicable quality standards
  • Premise plumbing (i.e. a building’s hot and cold water piping systems) is designed and maintained in a way that minimizes growth and spread of waterborne pathogens in both the supply and waste sides
  • Exposure to infection risks from water sources is minimized

Healthcare facilities can have large complex water systems that promote growth of pathogenic organisms if not properly maintained. For this reason, the Centers for Medicare & Medicaid Services (CMS) and CDC consider it essential that hospitals and nursing homes have a water management program that is effective in limiting Legionella and other opportunistic pathogens of premise plumbing from growing and spreading in their facility.

A healthcare water management program identifies both hazardous conditions and corrective actions that can minimize the growth and spread of waterborne pathogens. Programs such as Developing a Water Management Program to Reduce Legionella Growth and Spread in Buildings: A Practical Guide to Implementing Industry Standards 13.2 are designed, implemented, and regularly reviewed by multidisciplinary teams that include facility managers, infection prevention professionals, clinicians, and administrators.

On the “upstream” side, system disruptions or pressure drops, loss of disinfection residual (e.g. low chlorine levels), and main breaks are all factors that can impact the quality of water within a healthcare system. Thus, engagement with representatives from the local water utility is encouraged; hospitals and healthcare systems are often among a water utility’s largest customers. Water utilities represent important stakeholders in the effort to assure patient safety.

Similarly, moving “midstream,” water management programs should carefully assess their facility’s premise plumbing. This includes examining factors such as: the age and overall design of the system; additions, renovations and other modifications; water age (i.e. how long water might be held in the piping system); and assuring that there are no ‘dead ends’ where water can stagnate.

Finally, when focusing “downstream,” water management programs should consider the various pathways that might lead to patients becoming exposed to waterborne pathogens, in relation to ingestion, diet, hygiene, and clinical care. This is particularly important for patient populations whose ‘immune system might be compromised as a result of an underlying condition (e.g., cancer patients, premature infants) or in relation to invasive procedures such as surgery or the use of medical devices.

Sinks, Drains, Plumbing

Recent evidence indicates sinks and other drains, such as toilets or hoppers, in healthcare facilities can become contaminated with multidrug-resistant organisms (MDROs). These pathogens can stick to the pipes to form biofilms, which allow the organisms to persist in drains for long periods of time and are often difficult to impossible to fully remove. Because different types of bacteria may contaminate the same drain, drains can serve as sites where antibiotic resistant genes are transferred between bacterial species.

Patients may be exposed to organisms in drains when water splashes from the drain. Splashes may occur when water flow hits the contaminated drain cover or when a toilet or hopper is flushed. Splashes can lead to dissemination of MDRO-containing droplets, which in turn may contaminate the local environment or the skin of nearby healthcare personnel and patients.

The following measures can reduce the risk of these events from occurring in healthcare facilities:

  • Clean and disinfect surfaces near the drain, including the sink basin, faucet, faucet handles, and surrounding counter top at least daily.
  • Avoid placement of patient care items or personal items on counters next to sinks. While assuring that handwashing sinks are located close by and accessible to personnel responsible for preparing patient medications, avoid locating sinks adjacent to medication preparation areas unless barriers are in place to prevent splashing in medication preparation areas.
  • Prevent faucets from discharging directly above the drain as this causes splashing (i.e., angle water away from the drain or offset the faucet from the drain). When installing new sinks, consider selecting designs that prevent splashing. (Reference FGI Guideline for Hospitals A2.1- (1) a.)
  • Use sinks in patient care areas with adequate depth and the maximum water flow as regulated to prevent splashing (FGI Guideline for Hospitals A2.1- (1) a., b., c. and A2.1- (2) (5), (6) and Gestrich, Donskey et al ICHE 2018 A multicenter investigation to characterize the risk for pathogen transmission from healthcare facility sinks.)
  • Install and utilize hopper and toilet covers. These covers should be closed before flushing. If such covers are not available or are prohibited due to local plumbing or building code, close any door that separates the hopper or toilet from other patient care areas before flushing to contain any resulting environmental contamination. (Reference Mathers et al. Clinical Infectious Diseases 2018 Intensive Care Unit Wastewater Interventions to Prevent Transmission of Multispecies Klebsiella pneumoniae Carbapenemase-Producing Organisms.)
  • Do not discard patient waste down sinks and minimize discarding liquid nutritional supplements or other beverages down sinks or toilets.

Multiple interventions have been attempted to reduce the burden of pathogens in contaminated drains. In general, biofilms are difficult to completely remove despite chemical interventions; EPA recently approved products to clean and disinfect bacteria in healthcare facility wastewater drain biofilms. Some chemical interventions may reduce the amount of contaminated splashing that may occur from the drains and may have been useful in responding to outbreaks, but the most appropriate method remains unclear (The Hospital Water Environment as a Reservoir for Carbapenem-Resistant Organisms Causing Hospital-Acquired Infections-A Systematic Review of the Literature.)


At the intersection of research and innovation, the Division of Healthcare Quality Promotion (DHQP) researchers have designed and built a dedicated sink gallery for further defined study of intentionally contaminated plumbing to develop sampling schemes and understand factors affecting persistence, biofilm development, and remediation.

Collaboration is essential to advance public health research. DHQP areas of study include:

DHQP is collaborating with the University of Virginia Health System to study dispersal mechanisms from contaminated sinks. Results of this study, Droplet- Rather than Aerosol-Mediated Dispersion Is the Primary Mechanism of Bacterial Transmission from Contaminated Hand-Washing Sink Traps, suggest that microorganisms will disperse from contaminated sink bowl and drain surfaces primarily as large droplets that are generated during faucet usage.

DHQP-funded research has demonstrated that carbapenemase-producing strains of bacteria will colonize microbial biofilm communities in laboratory model systems simulating a sink drain P-trap (a section of pipe that holds water). These antibiotic-resistant organisms do not appear to amplify unless supplemented with liquid wastes containing microbial nutrients, including but not limited to soft drink products, intravenous fluids, or nutritional shakes.

DHQP researchers study non-traditional treatment strategies for the remediation of resistant organisms in contaminated handwashing sinks and plumbing systems in healthcare facilities involving use of lytic bacteriophages (bacterial viruses) with or without nonionic surfactants.

DHQP researchers are collaborating with the University of Utah on a research study to elucidate variables most critical to survival and amplification of antimicrobial resistant-gram negative bacteria and healthcare-associated pathogens in the healthcare environment.

Opportunistic Pathogens of Premise Plumbing

Gram negative bacteria
  • Pseudomonas aeruginosa
  • Pseudomonas putida-P. fluorescens
  • Burkholderia cepcia complex (B. cepacia, B. cenocepacia, at least 8 other genomospecies)
  • Cupriavidus (Ralstonia) pauculus
  • Herbaspirillium
  • Methylobacterium spp
  • Ralstonia pickettii, Ralstonia mannitolilytica
  • Sphingomonas paucimobilis, Sphingomonas mucosissima, other Sphingomonas spp
  • Stenotrophomonas maltophilia
  • Acinetobacter baumannii, complex A. calcoaceticus
  • Alcaligenes xylosoxidans, A. faecalis
  • Aeromonas hydrophila, Aeromonas spp
  • Elizabethkingia anophelis, E. meningosepticum
  • Legionella pneumophila
Non-fecal coliforms
  • Enterobacter cloacae
  • Klebsiella spp
  • Pantoae aggloerans
  • Rahnella aquatilis
  • Serratia liquifaciens, Serratia marcescens
Nontuberculous mycobacteria (NTM or Environmental Mycobacteria)
  • Mycobacterium. abscessus clade (M. abscessus, M. bolettii, M. massiliense)
  • M. chelonae
  • M. mucogenicum clade (M. mucogenicum, M. phociacum)
  • M. fortuitum clade (M. fortuitum, M. cosmeticum, mageritiense, M. porcinum, M. septicum)
  • M. immunogenum
  • M. smegmatis clade (M. goodii, M. wolinskyi)
  • M. aurum
  • M. simiae
  • M. avium complex (M. avium, M. intracellulare, M. chimaera, M avium ss hominissuis, M. columbiense)
  • M. scrofulacuemA. calcoaceticus
  • M parascrofulaceum
  • M. xenopi
  • M. arupense
  • M. kansasii
  • M. haemophilum
  • M. nonchromogenicum clade (M. nonchromogenicum, M. triviale, M. terrae)
  • M. gordonae (only among patients with severe immune deficiency)
Other bacteria/actinomyces
  • Microbacterium spp
  • Tsukamurella spp
  • Rhodococcus equi, Rhodococcus spp
  • Gordonae spp
  • Yeasts (eg. Candida parapsilosis, C. tropicalis)
  • Aspergillus fumigatus, A. niger
  • Fusarium spp
  • Exophiala spp
  • Acanthamoeba spp
  • Vermamoeba vermiformis
  • Naegleria spp

Further Reading

Commentary and International Guidance

Arduino MJ. Tap Water Avoidance Decreases Rates of Hospital-onset Pulmonary Nontuberculous Mycobacteria: A Call for Water Management in Healthcare. Clin Infect Dis. 2021;73(3):528-530.

Bartram J, Cotruvo J, Exner M, Fricker C, Glasmacher A. Heterotrophic plate count measurement in drinking water safety management: Report of an Expert Meeting Geneva, 24–25 April 2002. Int J Food Microbiol 2004; 92(3):241-7

Department of Health.  Health Technical Memorandum 04-01: Safe water in Healthcare Premises, Part A-Design, installation and Commissioning [PDF – 94 pages],  Crown Publishing, The National Archives, Kew, London, UK, 2016

Department of Health. Health Technical Memorandum 04-0, Part B- Operational Management [PDF – 98 pages],  Crown Publishing, The National Archives, Kew, London, UK, 2016

Department of Health.  Health Technical Memorandum 04-01, Part C: Pseudomonas aeruginosa, advice for augmented care units [PDF – 20 pages], Crown Publishing, The National Archives, Kew, London, UK, 2016

SAC. Guidelines for the Prevention and Control of Infection from Water Systems in Healthcare Facilities [PDF – 100 pages], Health Protection Surveillance Centre, Health Service Executive, Dublin, Ireland, 2017

WHO. Water safety in buildings [PDF – 164 pages], WHO, Geneva, 2011.

Sinks, Drains and Wastewater

Carlin PC. Wastewater drains: epidemiology and interventions in 23 carbapenem-resistant organism outbreaks. Infect Control Hosp Epi 2018; ahead of print; doi:10.1017/ice.2018.18.

Constantinides B, Chau KK, Quan TP, Rodger G, Andersson MI, Jeffery K, Lipworth S, Gweon HS, Peniket A, Pike G, Millo J, Byukusenge M, Holdaway M, Gibbons C, Mathers AJ, Crook DW, Peto TEA, Walker AS, Stoesser N. Genomic surveillance of Escherichia coli and Klebsiella spp. in hospital sink drains and patients. Microb Genom. 2020 Jul;6(7):mgen000391. doi: 10.1099/mgen.0.000391. PMID: 32553019; PMCID: PMC7478627.

Decraene, V., Phan, H. T. T., George, R., et al. A Large, Refractory Nosocomial Outbreak of Klebsiella pneumoniae Carbapenemase-Producing Escherichia coli Demonstrates Carbapenemase Gene Outbreaks Involving Sink Sites Require Novel Approaches to Infection Control. American Society for Microbiology. 2018; 62(12).

Heireman L, Hamerlinck H, Vandendriessche S, Boelens J, Coorevits L, de Brabandere E, et al. Toilet drain water as a potential source of hospital room-to-room transmission of carbapenemase-producing Klebsiella pneumoniae. J Hosp Infect 2020; 106(2):232-9

Hopman J, Tostmann A, Wertheim H, Bos M, et al. Reduced rate of intensive care unit acquired gram-negative bacilli after removal of sinks and introduction of ‘water-free’ patient care. Antimicrob Resist Infect Control 2017;6:59.

Mathers AJ, Vegesana K, German Mesner I, Barry KE, Pannone A, Baumann J, Crook DW, Stoesser N, Kotay S, Carroll J, Sifri CD. Intensive Care Unit Wastewater Interventions to Prevent Transmission of Multispecies Klebsiella pneumoniae Carbapenemase-Producing Organisms. Clin Infect Dis. 2018 Jul 2;67(2):171-178. doi: 10.1093/cid/ciy052. PMID: 29409044.

Park SC, Parikh H, Vegesana K, Stoesser N, Barry KE, Kotay SM, Dudley S, Peto TEA, Crook DW, Walker AS, Mathers AJ. Risk Factors Associated with Carbapenemase-Producing Enterobacterales (CPE) Positivity in the Hospital Wastewater Environment. Appl Environ Microbiol. 2020 Nov 24;86(24):e01715-20. doi: 10.1128/AEM.01715-20. PMID: 32917755; PMCID: PMC7688209.

Shaw E, Gavaldà L, Càmara J, Gasull R, Gallego S, et al. Control of endemic multidrug-resistant Gram-negative bacteria after removal of sinks and implementing a new water-safe policy in an intensive care unit. J Hosp Infect. 2018;98(3):275-281. doi: 10.1016/j.jhin.2017.10.025.

Volling, C., Ahangari, N., Bartoszko, J. J., et al. (2020). Are Sink Drainage Systems a Reservoir for Hospital-Acquired Gammaproteobacteria Colonization and Infection? A Systematic Review. Open forum infectious diseases8(2), ofaa590.

Weinbren M, Inkster T, Lafferty F.  Drains and the periphery of the water system – what do you do when the guidance is outdated? Infect Prev Pract 2021;3(4):100179

Weingarten, R., Johnson, R. C., Conlan, S. et al. Genomic Analysis of Hospital Plumbing Reveals Diverse Reservoir of Bacterial Plasmids Conferring Carbapenem Resistance. mBio. 2018;9(1).

Healthcare Water Management

Meeting water quality standards, limiting infection risks from water sources, and designing and maintaining premise plumbing to minimize the growth and spread of pathogens are vital components of a water management program. </p>

The following resources provide examples of the role of waterborne pathogens in healthcare.

Outbreaks Involving Waterborne Pathogens

Outbreaks involving waterborne pathogens are one of the more common types of consultation requests that CDC/DHQP receives. The following resources provide examples of review papers, commentaries, and outbreak investigation summaries.