Since the 80’s some cases of waterborne Healthcare Associated infections (HAIs) were described, but this concern was really taken into consideration in France during the 90’s, in relation with the Mycobacterium xenopi outbreak in the « Clinique du Sport » in Paris from 1993 to 1999 (1). A first case of osteomyelitis after endoscopic nucleotomy was reported in june 1993, inducing investigations which evidenced 9 cases, all operated in this clinic under endoscopy from 1988 to 1993. The origin of this contamination was associated with the final rinsing of the endoscopes with water considered as « sterile » but containing an slow growing atypical mycobacterium, Mycobacteriun xenopi, originally present in the drinking water distribution system of the city of Paris. In 1995 10 new cases were discovered, all operated during the same period ; more investigations allowed to detect 30 additional cases between 1995 and 1997 leading to a more proactive action leading to detect 14 more cases. Total   58 total cases.

At this period appeared clearly the need to publish guidelines for the use of water in hospital settings ; thus a multidisciplinary ad’hoc group was requested by the Ministry of Health to begin to work on this topic. During the preparation of these guidelines occurred the famous Legionellosis outbreak just after the opening of the Georges Pompidou European hospital in Paris with 11 cases (5 fatal issues) between december 2000 and june 2001 (2).

For the first time a large use of Point-of-Use Filters (PoUF) was organized. The consequences of these two mediatic outbreaks leaded the French Ministry of Health to circularise dedicated  Prevention of these Waterborne HAIs before the final editing of the official « Guide de l’Eau » in 2005 (3). Some concerns related to their technical and financial consequences did delay the publication of these guidelines. During the same period some authors highlighted the waterborne infectious risk in hospital settings, both in the US and in Europe (4,5).

« Healthcare Water Guidelines ».

The target of these guidelines were to :

  • Address the quality of water in healthcare settings and inform all players that the technological progresses and continuously increasing severity of cares and patient’s status induce the need to use something else than the drinking tap water even in accordance with the potability standards,
  • Identify the most hazardous microorganisms and the main infectious risks associated to the different uses of water during cares (risk assessment process),
  • Propose some elements for an adequate organization for the strategy of risk management,
  • Give recommendations for Water Quality according to the different uses of water,
  • Define some rules for both the technical design and the maintenance of production and distribution water networks.

It is necessary to remember these guidelines were written more than 25 years ago. Since this period, both the scientific and technical progresses were very important, thus some aspects of these guidelines are no more up-to-date and need to be refreshed.

The different matters of thinking during the preparation of these guidelines were the involved microorganisms and the associated risks, the need of adequate networks and the definition of critical points for their survey, the immunological status of the more and more sensitive patients, the need of Microbial quality criteria for the different uses of water and the definition of indicators allowing the quality insurance. Thus were defined the water at « the point of use » , the water for standard cares, the “Bacteriologically Controlled Water” (BWC) and other water qualities for very specific uses.

Simultaneously were defined some quality indicator parameters like heterotrophic plate count (HPC) at 22 and 36 °C, Pseudomonas aeruginosa and Legionella pneumophila for some specific uses, in addition to the classical faecal contamination indicators used for the drinking water standards.

One major recommendation of this guide was to organize in each setting a water committee, associating the different local players, for a common brain storming on the specific problems linked to the practices, the existing building and networks and the necessary preventive measures. It is important to note that all countries which decided to set a policy in this field recommend to install the same committee. This pinpoint the indispensable character of this common work for an efficient control.

The different water categories.

Four general water categories were defined in these guidelines, with sub-categories according to the various uses and the absence or the setting of specific treatment:

  • 1. Water distributed without treatment after its introduction in the building from the municipal drinking distribution system ; this water is used for drinking and sanitary purposes for the immunocompetent persons,
  • 2.Treated waters distributed inside the healthcare setting in accordance with defined quality criteria function of the different uses : drinking, sanitary or cares uses  which will be described below,
  • 3. Sterile waters defined by the Pharmacopeia and their different uses,
  • 4. Technical waters.

The Q.1. Quality: water which is not subjected to, or doesn’t require any further treatment:

Drinking water as it enters the hospital from the city distribution network (HPC target level <100CFU/mL at 22°C). The water at the points of use should conform the potability criteria with no variation of the HPC in a ratio of 10 to the value on entry + target level <1CFU/100mL for Pseudomonas aeruginosa. The different uses are Q .1.1., water used for drinking and food preparation and Q.1.2., water for standard cares, normal personal hygiene purposes like bathing, hand washing, showering of non-at-risk persons, surfaces cleaning, etc…

The Q.2. Quality: waters which are treated inside the hospital to achieve the risk assessment based criteria which have been defined appropriate depending on type of patient’s cares. This category includes the following sub-categories :

  • 2.1 Bacteriologically Controlled Water (Point-of-Use Filters) which meets defined microbiological criteria for defined patient uses: cares for at risk patients or inducing a risk for the patient.
  • 2.2. Distributed hot water,
  • 2.3. Water for hydrotherapy,
  • 2.4. Water for specific uses like in dermatology departments or for defined equipment used in patient treatments like sonication baths, dental chairs, birthing pools, spas and whirpools, etc..
  • 2.5. Water for haemodialysis,
  • 2.6. Purified water,
  • 2.7. Ultrapurified water,
  • 2.8. Water for refrigerated drinking fountains,
  • 2.9. Water used as rinsing water for critical medical devices.

The Q. 3. Quality includes the sterile waters:

  • 3.1. Water for injectable products (see Phamacopea 2006),
  • 3.2. Water for irrigation of wounds (see WHO 2006).
  • 3.3. Sterile drinking water for deeply immunodepleted patients.

The Q.4. Quality includes different kinds of waters for technical purposes like fire department, sterilization department, heating and cooling fluids, linen cleaning. These categories were not addressed in the guidelines because of the lack of necessary knowledges during the redaction’s period.

The Microbial Quality Limits.

Because of the absence of the necessary knowledges and the difficulty to perform a full risk assessment process for some parameters, it has been decided to propose a more pertinent approach with the setting of 3 levels of quality (target, alert, reinforced action) for each parameter proposed as a quality indicator, with the colours used for traffic lights. This has been reproduced at the international level, indicating this was not stupid. This approach, even criticized by some simpflying spirits, allows to take into account the safety margin linked to the sample and the microbiological analysis. This is also pedagogical and includes to some extend a medico-legal protection. We need to remember the uncertainties linked to the sampling and the analytical processes ; thus a result of X CFU/100mL must be considered as included between ½.X and X+ ½.X. If the imperative limit value would be X , the decision of the court to declare the hospital guilty could be erroneous if the result is around X.

The target value is the « ideal » value. The alert value indicates a certain level of risk which induces the need to face with the reasons of this increase of this parameter and to take corrective measures with an improved follow-up. The reinforced action limit value induces to avoid immediately any patient’s exposure and to perform the necessary actions for being back around the target level or, at least, below the alert level. The demonstration of an admissible level of risk with the aid of analyses is necessary before using this water for patient’s cares.

As an example, this is the table of the proposed values for quality Q.1.1.

The Bacteriologically Controlled Water – Water Free of Microorganisms was a new concept for clarifying the difference with the real sterile waters, introducing a new quality of water, microbiologically safe for the following uses:

  • Contact with mucosa,
  • Final rinse of medical devices,
  • Cares given to high-risk patients (transplanted, immunosuppressed, prolonged corticotherapy …).

The quality parameters for this BCW are presented in the following table:

For obtaining this quality, the « Guide de l’Eau » initially recommended the use of a chemical (ex: hyperchlorination followed by dechlorination) or physical (filtration, UV, heat) treatment. But the data collected during the last two decades indicated clearly that the POU Filtration was the safest, less expensive and simplest solution.

Particular cases: Legionella and Pseudomonas aeruginosa.

Legionella : The Legionellosis risk was taken into account for water used for the shower and hydrotherapy. The hot water for shower includes two sets of levels according to the immunological status. For classical patients, the alert level is > 1,000 CFU of Legionella pneumophila per liter. For high-risk patients it is necessary to avoid the presence of any Legionella, thus the analytical detection is the alert level (actually < 10 CFU/L). These different limit values are presented in the Table…Only Legionella pneumophila has been taken into consideration because involved in France in more than 97% of the Legionellosis cases in healt care settings.

This alert value for high-risk patients may only be reached using PoUFilters. For classical patients the target level may also be reached in a well-designed and maintained distribution network including a loop between 60 and 55 °C, without chemical disinfection which is not considered as an alternative in France.

Critical values for the control of Legionellosis proposed in the water guidelines:

Immunocompromized patient        classical patient

Target level               < Detection Limit Value             1,000UFC L.pneumophila/L

Alert level                  = Detection Limit Value           >1,000UFC L.pneumophila/L

Unacceptable level  > Detection Limit Value          =10,000UFC L.pneumophila/L

Pseudomonas aeruginosa: The risk linked to waterborne Gram negative bacteria, like Pseudomonas aeruginosa involves other patients and others cares. This microorganism was chosen as an indicator because a high prevalence of presence in the networks of intensive care units, where the waterborne origin of the infections in around 50% of all cases.

Numerous families of hydrophilic bacteria are also able to induce such infections like Acinetobacter, Burkholderia, Sphyngomonas, etc… Like Pseudomonas they are able of antimicrobial resistance acquisition and more and more involved in the severe HAIs in intensive cares units. Prevention is achieved by increasing the distance between the patient and the water point of the room, by fitting a POU Filter on this tap and trying to limit the risk of aerosol’s generation issued from the sink’s siphon. Using in 2005 the precautionary principle, it was decided to set a limit of <1/100mL for Pseudomonas aeruginosa in the MCW (Detection Limit).

The more recent UK Guidelines in 2012 incopores the principle of the 3 levels with the following values ; target level <DL , alert level between 1 and 10 CFU/100mL, reinforced action >10 CFU/100mL.

In this context the use of Point-of-Use Filters increased regularly because considered as the most simple and reliable solution for obtaining the garantee to respect this limit for all Gram- bacteria and insure the prevention of waterborne HAIs for patients at risk and high-risk (6). The high-risk patients are hospitalized in specific wards dedicated to the treatment of leukemia with bone marrow transplantation, organ transplantations and treatment of severe cancers or immunity deficits. The patients at risk are those hospitalized in intensive care units where catheters and artificial ventilation are the possible entry points for the microorganisms trough aerosols in the room or the cleaning of the patient. In all these cases, the Point of Use Filter is a reliable preventive solution. Microbiological sampling of the water networks in these wards need to be regularly performed. The microorganisms isolated with the aid of these analyses need to be compared by molecular biology methods to the strains isolated from patients during their routinely surveillance (often weekly) or in case of infection.


The work performed during the writing of this Healthcare Water Guidelines incorporated the now called risk assessment process proposed by WHO in the « Water Safety Plans », considered as essential in the European Directive for the quality of drinking water and used in the national decrees. This gives more interest to this process and incentive for continuing to take into account the newly described microbiological hazards (Free Living Amoebae able to host numerous bacterial and viral pathogenic agents, biofilms, antimicrobial resistance, Viable But Not Cultivable flora, etc …).

As a consequence of this risk assessment process, it is necessary to organize an environmental surveillance with sampling at critical points. We have to keep in mind a good control of waterborne HAIs may not only be based on this microbiological survey ; more important are an excellent design and maintenance of the networks and the surveillance of the strains isolated both in water and patients.

It is also necessary to involve all players via repeated pedagogical actions because their involvement is essential for a good result considering the patient’s risk, the performed cares and the respect of the bundles guarantying the quality.


Professor Philippe Hartemann


  1. Weber W. Paris’ Pompidou hospital plagued by setbacks. 2001. 9250 :130.
  2. C-CLIN Paris Nord. Infections du rachis à Mycobacterium xenopi à la Clinique du sport. Rapport d’investigation. 1999. Décembre : 70p.
  3. L’eau dans les établissements de santé. Guide technique publié par DGS-DHOS. Ministère de la Santé. France. 2005 : 128p.
  4. Anaissie EJ, Penzak SR,Dignani MC. The hospital water supply as a source of nosocomial infections : a plea for action. Intern. Med. 2002. 162 :1483-1492.
  5. Exner M, Kramer A, Lajoie L, Engelhart S, Hartemann P.Prevention and control of healthcare-associated waterborne infections in health care facilities. J. Infect. Control. 2005. 33(Suppl 1) : S26-40.
  6. Grondin V, Payol F, Raymond M. Cost-effectiveness of point of use water filtration for waterborne infection. 2018.1-6.

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