Based on the RSPH webinar Back to Basics: Waterborne Pathogens in Healthcare, presented on 24 June 2026 and sponsored through an educational grant from Pall Medical.

Introduction

For many years, healthcare water safety has been viewed primarily through the lens of compliance. If water meets regulatory standards and Legionella controls are in place, systems are often considered safe. However, healthcare environments are changing. Hospitals care for increasingly vulnerable patients, infrastructures are becoming more complex, and antimicrobial resistance is rising. As a result, water safety is now recognized as a core patient-safety issue rather than simply a facilities-management responsibility.

“Compliant drinking water is not sterile and may not be safe for every patient.” 
Dr. Surman-Lee

Drawing on more than 40 years of experience in microbiology, outbreak investigation, and healthcare water safety, Dr. Surman-Lee argued that organizations must move beyond a Legionella-focused approach and adopt a broader, whole-system strategy to managing waterborne risks. Her message was clear: the future of healthcare water safety lies not in reacting to outbreaks, but in preventing the conditions that allow pathogens to thrive.

Looking Beyond Legionella

Legionella remains an important healthcare pathogen, but it is only part of the challenge. The webinar highlighted growing concerns around Pseudomonas aeruginosa, non-tuberculous mycobacteria (NTM), and antimicrobial-resistant organisms. These pathogens behave differently and often require different control measures. The scale of the problem is significant.

The European Centre for Disease Prevention and Control reported more than 15,000 Legionnaires' disease cases in Europe during 2024, representing a 6.3% increase from the previous year and the highest total recorded since surveillance began. Reported cases in the United States have increased approximately ninefold since 2000.

At the same time, resistant waterborne pathogens create substantial clinical and economic burdens. A Spanish study discussed during the webinar found that 29.6% of 402 Pseudomonas aeruginosa infections involved resistant strains. Multidrug-resistant cases were associated with substantially higher costs, reported as €15,265 per case compared with €4,933 for non-resistant infections. German data showed that around 15% of hospital-acquired Pseudomonas pneumonia cases were multidrug resistant, adding roughly $19,000 per infection.

Why Water Systems Become Reservoirs

Water is used throughout healthcare facilities for drinking, washing, environmental cleaning, medical equipment, and patient care. Small numbers of microorganisms are naturally present in drinking water and are generally harmless to healthy individuals. However, healthcare patients often have weakened immune systems and are far more susceptible to infection. One of the most important concepts discussed in the webinar was the role of biofilms. These microbial communities form on wet surfaces within pipes, tanks, valves, drains, and outlets. Once established, biofilms can make microorganisms substantially more tolerant of disinfectants, heat and other control measures.

Biofilms can also provide a habitat for protozoa that harbor pathogens such as Legionella. This means that routine water testing may capture only a snapshot of conditions within a system, while larger microbial populations remain hidden within biofilm layers. As Dr. Surman-Lee explained, what is detected in a water sample may represent only the visible portion of a much larger problem. 

A Powerful Outbreak Lesson

One of the webinar's most striking examples involved an outbreak in which 17 patients died within three months, with infections causing or contributing to 12 of those deaths. Investigators traced the source not to drinking water but to handwashing sinks used by healthcare staff. Contaminated droplets were found to spread up to one meter from sinks, and other investigations have documented sink-associated spread at even greater distances. The outbreak was ultimately controlled by preventing contaminated splashing from the sinks. The case reinforced an important lesson: infection risk is often linked not only to microorganisms themselves but also to infrastructure design, drainage, splash zones, and routes of exposure. Effective control measures must address the entire system.

Prevention Is Better Than Remediation

A central theme throughout the webinar was the importance of prevention. Water systems can become contaminated during manufacturing, transportation, storage, installation, testing, or commissioning. Poor installation practices and stagnant water create opportunities for microorganisms to establish themselves before patients even enter a building. Once mature biofilms develop, complete removal becomes extremely difficult. For this reason, preventing contamination from entering and colonizing water systems is typically more effective than attempting to eliminate it later. Proper commissioning, flushing, validation, and verification are essential steps in reducing long-term risk.

The webinar also highlighted the growing importance of wastewater management. Drain biofilms can act as reservoirs for pathogens and as environments where antimicrobial-resistance genes may spread. Modern water-safety programs therefore need to address the full water cycle, including wastewater systems and drainage infrastructure.

Conclusion

Fifty years after the 1976 Philadelphia outbreak, healthcare organizations possess more knowledge and guidance than ever before. Yet reported cases of Legionnaires’ disease continue to rise in many countries, patient populations are becoming more vulnerable, and antimicrobial resistance remains a growing concern.

The webinar's conclusion was clear: compliance alone is not enough, testing alone is not enough, and reacting to outbreaks is not enough. Healthcare organizations must adopt a proactive, whole-system approach focused on prevention and risk management. Ultimately, protecting water systems means protecting patients. Water safety is patient safety.

Our sincere thanks go to Dr. Surman-Lee for delivering this insightful webinar. Her expertise, practical experience, and passion for improving patient safety provided valuable perspectives for all attendees.

Author bio

Dr. Luibl is a Sr. Marketing Manager Medical Content with knowledge in medical device and clinical science.