Engineer healthcare water systems for infection prevention
The design of hot and cold water distribution systems and plumbing in a healthcare environment (hospitals and long-term care facilities) can impact the prevalence and transmission of waterborne pathogens. Healthcare water systems need to be engineered and maintained in a way that minimizes the growth and spread of microorganisms to reduce risks of healthcare associated infections (HAI) 1,2.
Understanding the aspects of water system design that increase the risks of waterborne pathogen growth and transmission is essential in order to mitigate risks at the design stage, or to implement preventative strategies in existing buildings. Point-of-use filtration at faucets is an easily accessible, quick to implement method to reduce water-to-patient transmissions.
Hospital tap water is a source of patient infection
Intensive Care Unit (ICU) tap water has been identified as a significant source of exogenous Pseudomonas aeruginosa isolates. A review of studies showed that up to 50% of infection/colonization episodes in patients were due to genotypes found in ICU water3.
When engineering hospital water systems for infection prevention, a combination of control measures are required: mechanical, operational, and chemical.
Design healthcare water systems for hand hygiene
Hand hygiene is essential to safe hospital care. The plumbing infrastructure including the design and placement of sinks, faucets, and hand-drying facilities, plays an important role in maintaining infection control. The building design can facilitate or impede proper hand hygiene behavior by healthcare personnel, affecting transmission of microbes.
Sink design may facilitate the spread of pathogens
- The location of sinks is more influential than the number of sinks.4
- Each additional meter between the patient’s immediate surroundings and the nearest sink decreased the likelihood of handwashing by 10 percent. 4
- Aerosols and splashes from contaminated handwashing sinks have been implicated as the source of outbreaks resulting in patient infection and death.4
- Sink design may facilitate the spread of pathogens by promoting formation of biofilm or by encouraging disruption of established biofilm, resulting in aerosolization, splashing, or contamination of adjacent surfaces.5
Hospitals should consider developing a surveillance and prevention strategy based on the current design and state of their sinks.5
Hospital faucets can harbor potential pathogens
- Syndor et al. found 95% of sensor taps to be contaminated with Legionella spp. vs. 45% of manual taps.6
- Investigation of an outbreak of Pseudomonas aeruginosa in ventilator-dependent infants at a Los Angeles County NICU (Neonatal Intensive Care Unit) found 75% of sensor taps vs. 0% of manual taps were positive for Pseudomonas aeruginosa contamination.7
- Types of faucet and connecting pipes, flow rate, and water quality have been found to be important parameters influencing the prevalence and the concentrations of P. aeruginosa in faucets, with concentrations up to 100 times higher in the first 250 mL of water before flushing.8
- Aerators and laminar flow devices have been a known risk for healthcare-associated infection for over 50 years.9
Water temperature control is essential but depends on good design
Temperature can act as a control measure to prevent Legionella multiplication and maintain biofilm stasis. 10 In a review of regulations worldwide for hot water temperatures and water storage Van Kenhove et al. summarized similarities in current regulations:11
- Cold water storage and distribution temperatures should be below 77º F
- Keep hot water temperature above 140º F when leaving the tank and at or above 131º F in circulation and distribution pipes
- It should be possible to achieve a temperature of 158º F at every tap for thermal shock treatment
- Regular inspection of equipment where temperature control cannot be maintained within the preferred range
- Cold and hot water pipes should not be located too close to each other to prevent heat transfer.
- Empty storage vessels for regular cleaning and maintenance
- Keep stored water volume small
However, there can be obstacles to maintaining these conditions depending on the water system design:10
- Water heater capacity not capable of providing sufficient volume at temperatures necessary to kill Legionella
- Scalding and plumbing code requirements
- Increased corrosion
- Increased sediment/turbidity
- Decreased equipment life
- Microbial resistance to thermal shocks
Pipe design and dead legs are common water system problems
The goals in healthcare water system design are to minimize water stagnation, heat loss/gain, and increase flow. Commonly encountered problems with water system design include:
- Poor flow or uninsulated pipes
- Warm and cold water pipes are frequently installed in the same duct.
- Temperature transmission between warm and cold water (e.g. during heat and flush treatment > 158 °F).
- Reconstruction measures may result in dead ends. Dead ends will result in no-flow conditions and improper temperature control. Temperatures outside of microbial control ranges will allow proliferation.
Plumbing materials can encourage biofilm formation
Parkes et al. states “Materials used in hospital piping should be taken into consideration, given that plastic has been shown to encourage biofilm formation more than copper or stainless steel”. 5 Shaw et al. implicated plastic P-traps as one of a number of sink design features that might have contributed to a high incidence of MDR Gram-negative bacilli (GNB) infections in their ICU.11
Low-flow fixtures pose a risk in healthcare water systems
The National Academies of Sciences, Engineering, and Medicine have stated that “Low-flow fixtures should not be allowed in hospitals and long-term care facilities because of these buildings’ high-risk occupant populations.” “Because of their lower flow, these fixtures increase water age and restrict disinfectant levels, including the disinfection provided by elevated water temperatures. As such, low flow fixtures present a greater risk for Legionella development in the plumbing systems that feed them.”12
Point of Use water filtration: quick connection, immediate protection
While full consideration of water system design for infection prevention can be made in the development of a new healthcare facility, ongoing water system maintenance is essential. For many older healthcare facilities, there is a need to implement preventative measures to counteract risks from the existing plumbing system design.
Point-of-use water (POU) filtration can provide a reliable and effective solution for microorganism retention as part of a water management program. Quick to implement, Pall POU Water Filters are FDA 510(k) Cleared Class II Medical Devices for faucets, showers and ice machines. They are validated to act as a barrier to Legionella spp., Pseudomonas spp., and other opportunistic waterborne pathogens which may lead to patient infections.
Learn more: Point-of-use Water Filters
- Centers for Disease Control and Prevention, Healthcare Environmental Infection Prevention: Reduce the Risk from Water. Available at: https://www.cdc.gov/hai/prevent/environment/water.html [Accessed 2 June 2020]
- Centers for Medicare and Medicaid Services, Requirement to Reduce Legionella Risk in Healthcare Facility Water Systems to Prevent Cases and Outbreaks of Legionnaires’ Disease (LD), Ref: S&C 17-30-Hospitals/CAHs/NHs REVISED 06.09.2017. Available at: https://www.cms.gov/Medicare/Provider-Enrollment-and-Certification/SurveyCertificationGenInfo/Downloads/Survey-and-Cert-Letter-17-30.pdf [Accessed 2 June 2020]
- Trautmann, M., Lepper, P., & Haller, M., Ecology of Pseudomonas aeruginosa in the intensive care unit and the evolving role of water outlets as a reservoir of the organism. American Journal of Infection Control, Vol. 33 No. 5, S41-S49, 2005
- The Health Research & Educational Trust of the American Hospital Association, American Society for Health Care Engineering, Association for Professionals in Infection Control and Epidemiology, Society of Hospital Medicine, University of Michigan. Using the Health Care Physical Environment to Prevent and Control Infection. A Best Practice Guide to Help 1. Health Care Organizations Create Safe, Healing Environments. 2017
- Parkes, L. O., & Hota, S. S., Sink-Related Outbreaks and Mitigation Strategies in Healthcare Facilities. Current Infectious Disease Reports, 20:42 page 1-14, 2018
- Sydnor ER et al., Electronic-eye faucets: Legionella species contamination in healthcare settings. Infect Control Hosp Epidemiol 33:235–240, 2012
- Terashita D et al., An Outbreak of Pseudomonas Aeruginosa in the Neonatal Intensive Care Unit (NICU) and the Possible Role of Sensored Sinks. Am J Infect Control, 35, E134-E125, 2007
- Charron, D. B. Impact of Electronic Faucets and Water Quality on the Occurrence of Pseudomonas aeruginosa in Water: A Multi-Hospital Study. Infection Control & Hospital Epidemiology, 311-319 2015
- Cross, D. et al., The Faucet Aerator — A Source of Pseudomonas Infection. N Engl J Med 274:1430-1431, 1966
- Flemming, H-C., Executive Summary: Results of the collaborative research project “Biofilms in Drinking Water Installations”. Duisburg, Germany: University Duisburg-Essen. 2016
- Shaw E, 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. 98:275–81, 2018
- National Academies of Sciences, Engineering, and Medicine. Management of Legionella in Water Systems. Washington, DC: The National Academies Press. 2019 [online] https://doi.org/10.17226/25474