Legionella Risk Management in Healthcare Facilities

Health facilities are at particularly high risk of legionella infection. Their large, complex water and air conditioning systems are an ideal growth environment for this pathogenic bacterium.

By teamblog

Jan 14, 2020
Hospitals, retirement homes and clinics serve vulnerable populations, highly exposed to the most severe form of Legionnaires’ disease. As a result, health facilities are subject to stricter controls than other types of public buildings and must implement an efficient prevention strategy.

Patients vulnerability in health facilities

Patients in retirement homes, hospitals, clinics or care centers are by definition more likely to catch diseases than the rest of the population. Regarding legionella, highly vulnerable populations are immunosuppressed patients, recently transplanted, or cancer and immunotherapy patients. Other risk factors are an age over 50, tobacco userecent surgery, heart or lung conditions.

What type of equipment is likely to harbor legionella in health facilities?

All water supplies and cooling towers can be colonized by legionella. Hospital contamination points are usually showers, some air conditionershumidifiers or cooling towers .

Equipment features (aerosol generating devices, shower heads with no filter), lack of maintenance and cleaning, and water system characteristics (dead arms and areas of stagnation, multiple loops, corrosion, cold water subject to heat gain…) can promote legionella colonization.

Positive legionella resultWhat are the consequences of a Legionnaires’ disease outbreak in a health care facility?

A health facility tested positive for legionella following a patient infection may be subject to a temporary closure order by health authorities, depending on the outbreak severity. A significant financial shortfall may result as the risk manager will have to take action to eradicate the bacteria, which incurs biocides and heating costs to carry out disinfection and thermal shocks. Preventive measures must also be taken to prevent similar future occurrences. A legionellosis outbreak can seriously harm the hospital’s reputation and it may be difficult to regain public trust. Like Mount Carmel Grove City hospital, which recently made headlines, healthcare facilities can face civil and criminal prosecution in case of  risk management negligence. In that particular case, the contamination was due to improper water treatment that led to 16 Legionnaires’ disease cases, including one death.

What are the regulatory requirements for managing legionella risk in hospitals?

There is no current regulatory harmonization on a global scale for legionella risk management in health facilities. When guidelines do exist, they generally impose an annual water testing using the ISO 11731 (or NF T90-431) method for all critical points in their premises. As a general rule, legionella concentration should not exceed 1 000 CFU/L throughout the hot water system. This threshold may be reduced to 10 CFU/L in hospital departments containing high risk patients.

Due to the proliferation of legionella in warm waters, daily temperature checks are required to ensure that cold water remains below 25°C (77°F) and hot water is kept at more than 50°C (122°F). In addition, health facilities must ensure compliance of their water systems and carry out any necessary repair work to avoid providing an environment conducive to the growth of legionella.

All testing, maintenance and repair works must generally be documented and kept in a record made available to health authorities. This helps demonstrate that measures have been taken to address the risk and avoid liability in the event of an outbreak.

Get to know your water system to perform strategic legionella checks

It is strongly recommended to carry out regular water testing in order to determine the presence of legionella in water systems. Network mapping is a key element in risk assessment. By identifying the most representative points (most frequent points of use, areas supplying highly at-risk patients, newly renovated parts …) and areas at risk (return loops, the farthest points in production output and close to the most “vulnerable patients”, hot water tanks…) in your network, you will be able to adequately conduct routine test monitoring and take appropriate action immediately if threshold is exceeded, thus ensuring optimal patient safety.


Center for Disease Control and Prevention, Legionella, Guidelines, Standars and Laws, 2018, https://www.cdc.gov/legionella/resources/guidelines.html

European Centre for Disease Prevention and Control, 2019, Legionella, https://ecdc.europa.eu/en/legionnaires-disease

Ministère de la Santé et des Solidarités Direction Générale de la Santé, Conseil supérieur d’hygiène publique de France Section des maladies transmissibles, Section des eaux, Le risque lié aux légionelles Guide d’investigation et d’aide à la gestion, 2005 https://solidarites-sante.gouv.fr/IMG/pdf/guid2005-2.pdf

Ministère du Travail, de l’Emploi et de la Santé, Ministère des Solidarités et de la Cohésion Sociale, Circulaire DGS/EA4 no 2010-448 du 21 décembre 2010 relative aux missions des agences régionales de santé dans la mise en œuvre de l’arrêté du 1er février 2010 relatif à la surveillance des légionelles dans les installations de production, de stockage et de distribution d’eau chaude sanitaire, 2010, https://solidarites-sante.gouv.fr/fichiers/bo/2011/11-01/ste_20110001_0100_0130.pdf

WBNS-10tv, 2nd lawsuit filed after Mount Carmel Grove City Legionella outbreak, June 2019 https://www.10tv.com/article/2nd-lawsuit-filed-after-mount-carmel-grove-city-legionella-outbreak-2019-jun,

Get our free white paper on Legionella Risk Control in Healthcare Facilities

Did you like this article? Go further by reading our white paper that explains how to adopt the right reflexes to better control each point of the water system and avoid any risk of contamination.

Read More


Submit a Comment

Your email address will not be published. Required fields are marked *