Protecting High Risk Patients from Waterborne Infection

Patients undergoing bone marrow transplantation (BMT) are profoundly immunosuppressed.  Their susceptibility to even very low concentrations of environmental microorganisms including waterborne bacteria such as Pseudomonas aeruginosa, Legionella spp., non-tuberculous mycobacteria, Stenotrophomonas maltophilia), which would normally offer no threat to healthy or more mildly compromised individuals, becomes critical to manage.  Mucosal surfaces, our semipermeable skin barrier interface between the external environment and body, protect us hourly from casual infection.  BMT treatments impair this barrier leading to leakage and a gaping breach in immune defences.  Additionally, BMT patients are pancytopenic – meaning not only do they have very low numbers of white blood cells patrolling the body to defensively act, but they also have low red blood cells leading to poor tissue oxygenation plus extreme fatigue, and low platelets counts making them susceptible to bleeds.  These patients are at high risk within normal environments, and frequently need to be isolated within hospital, or at home, during their treatment.  How safe is it for them in the hospital environment?

Gaps in Hospital Design Approach

A recent literature search by Inkster and co-workers ( analysed papers from the start of this century and concluded that, whilst there are plentiful publications on the design and operation of high efficiency particulate air (HEPA) provision for BMT patients, there is nothing bespoke or dedicated to their supply of safe water, and little specific for their equipment and environmental surfaces.  Shameful.  It is time to target and specialise guidance for the design, material composition, installation, commissioning, operation and positive user behaviours for water systems for extraordinarily susceptible patient groups. 

What is clear from Inkster’s paper is that by delving into the numerous publications of nosocomial waterborne infectious outbreaks in the BMT patient group they were able to determine the

  • waterborne organisms of concern: Legionella spp., Pseudomonas aeruginosa, non-tuberculous mycobacteria, Stenotrophomonas maltophilia
  • sources contributing to outbreaks:  design of components such as taps with flow straighteners and aerators, poor materials of construction supporting microbial growth, water testing during component manufacture, lack of activity space between tap outlet and basin, splash from sinks into the patient zone, lack of daily flushing from under used outlets, sink traps and waste water
  • control measures understood to have prevented further outbreak cases and potentially improved water quality for ongoing patient care:  avoidance and restriction of water usage/exposure, installation of point-of-use water filters, replacement of contaminated water fittings, use of systemic biocide and improved environmental surface cleaning. 

Additionally, there is a wealth of potable water system guidance and documentation available.  Care must be taken to ensure that the relevant details needed are extracted without watering down or losing the impact of an holistic Water Safety Plan approach for the entire in-premise water supply. 

Interdisciplinary Team for Safe Design & Operation Guidance

Engineering, microbiological, hygienic and clinical application knowledge are required to piece together and create robust, relevant hazard and risk recognition in such compromised patient group areas.  Indeed, a multi-disciplined team of experienced experts to draw together relevant peer reviewed evidence and create the guidance as a best practice document is highly desirable.  Architects need to be part of the loop – to both give and receive information and to ensure future designs reflect best practice – otherwise the same errors will be made, and the lifetime of the in-premise water supply compromised because of them.

Embracing Waterless Patient Care

The presence of water outlets within high risk units or clean rooms is already in the spotlight with a steady stream of publications confirming that by removing water sources there is a reduction in Gram negative infections and a reduction in antibiotic usage (Catho, 2021; Hopman, 2017; Shaw, 2018; van der Zwet, 2022).  Convincing clinical staff that it is not necessary to have a handwash basin present in the room is a challenge, however, the level of supporting data is difficult to ignore, and the change in working practices found not burdensome.  For water to be present in high risk patient areas it should be proven that the water quality is under control and presents low threat for all potential users, with verification of control measures demonstrated clearly and transparently.  The planning phase of patient care units should pre-empt the need for extensive water control measures yet there remain considerable challenges with poor hygienic design for new healthcare build or refurbishment projects.

With the vulnerability of immunocompromised patient groups, the nature of their underlying conditions and current targeted treatment regimens, are today’s in-premise water systems safe enough for their provision?

We support Inkster’s call for expert input into specialised safe water design guidance for high risk patient groups. Would you agree?


  • Catho G, Martischang R, Boroli F, Chraïti MN, Martin Y, Koyluk Tomsuk Z, Renzi G, Schrenzel J, Pugin J, Nordmann P, Blanc DS, Harbarth S. Outbreak of Pseudomonas aeruginosa producing VIM carbapenemase in an intensive care unit and its termination by implementation of waterless patient care. Crit Care. 2021 Aug 19;25(1):301. doi: 10.1186/s13054-021-03726-y. PMID: 34412676; PMCID: PMC8376114.
  • Hopman J, Tostmann A, Wertheim H, Bos M, Kolwijck E, Akkermans R, Sturm P, Voss A, Pickkers P, Vd Hoeven H. 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 Jun 10;6:59. doi: 10.1186/s13756-017-0213-0. PMID: 28616203; PMCID: PMC5466749
  • Inkster T, Peters C, Dancer S. Safe design and maintenance of bone marrow transplant units: a narrative review. Clin Microbiol Infect. 2022 Apr 2:S1198-743X(22)00173-2. doi: 10.1016/j.cmi.2022.03.032. Epub ahead of print. PMID: 35378272.
  • Shaw E, Gavaldà L, Càmara J, Gasull R, Gallego S, Tubau F, Granada RM, Ciercoles P, Dominguez MA, Mañez R, Carratalà J, Pujol M. 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 Mar;98(3):275-281. doi: 10.1016/j.jhin.2017.10.025. Epub 2017 Nov 28. PMID: 29104124.
  • van der Zwet WC, Nijsen IEJ, Jamin C, van Alphen LB, von Wintersdorff CJH, Demandt AMP, Savelkoul PHM. Role of the environment in transmission of Gram-negative bacteria in two consecutive outbreaks in a haematology-oncology department. Infect Prev Pract. 2022 Feb 25;4(2):100209. doi: 10.1016/j.infpip.2022.100209. PMID: 35295671; PMCID: PMC8918851.

Share this post