Pseudomonas aeruginosa
Cities measured
87
Detected in
4 / 87
Elevated / alert
1
Highest
3 CFU/100mL — Beirut
Overview
P. aeruginosa is an opportunistic environmental bacterium that survives and multiplies in low-nutrient water environments including drinking water pipes. It is regulated in bottled water; in tap water, concern is concentrated in hospital and healthcare settings serving immunocompromised patients.
Health Relevance
P. aeruginosa causes life-threatening infections in immunocompromised individuals — burns patients, cystic fibrosis patients, transplant recipients, and ICU patients. It is intrinsically resistant to many antibiotics and is on the WHO critical priority list for new antibiotic development.
Regulatory Limits
Drinking Water Directive 2020/2184
0 per 250 mL for bottled natural mineral water. Not generally monitored in tap water.
Controversy & Contested Science
P. aeruginosa outbreaks in hospital water systems — including neonatal ICUs — have caused deaths across Europe, including clusters in France, Belgium, and the UK. Hospital water systems provide warm, slow-flow, biofilm-friendly conditions ideal for growth. A 2021 ECDC review found P. aeruginosa the most frequent Gram-negative pathogen in ICU water-associated outbreaks. No standardised EU regulation governs hospital water system design or P. aeruginosa monitoring — hospitals develop their own protocols with highly variable stringency, creating a persistent patient safety gap.