American microbiologist behind global water safety breakthrough wins 2026 Lee Kuan Yew Water Prize
- Written by Media Outreach
- Professor Joan Bray Rose recognised for pioneering Quantitative Microbial Risk Assessment (QMRA) as a global approach for assessing pathogen risks in water
- QMRA adopted into global drinking water standards and enabled safe water reuse, benefitting millions worldwide

Professor Joan Bray Rose, Homer Nowlin Chair in Water Research and Director of the Water Alliance at Michigan State University and Lee Kuan Yew Water Prize 2026 Laureate
2. Commenting on her accolade, Professor Rose, 11th recipient of the Lee Kuan Yew Water Prize said, "I am deeply honoured to receive this esteemed award. This recognition reflects our collective progress in advancing microbial risk science and its role in protecting public health today. Safe water is one of the world's most fundamental yet unevenly distributed resource critical to sustaining human life. As microbial risks continue to evolve, strengthening the robustness of our water systems remains an ongoing endeavour to ensure they remain dependable and resilient; safeguarding both water quality and people's lives." She is currently the Homer Nowlin Chair in Water Research, Director of the Water Alliance at Michigan State University. Uncovering invisible risks to revolutionise water safety 3. In the late 1980s and 1990s, Professor Rose led a team to investigate a series of waterborne disease outbreaks across the United States. Among the most severe was the 1993 Cryptosporidiosis outbreak in Milwaukee, Wisconsin, where an estimated 403,000 residents fell ill and at least 69 deaths were recorded[1]. She was the first to demonstrate the widespread occurrence of Cryptosporidium as a zoonotic pathogen[2] in the United States, and its transmission to humans through inadequately filtered and disinfected drinking water supplies. By establishing Cryptosporidium as the causative agent of these outbreaks, she highlighted the vulnerability of drinking water systems to microbial contamination – a challenge with global public health implications. Her findings also revealed a critical gap: pathogens could evade conventional water treatment, existing monitoring systems detected microbes without quantifying risk, and public health responses were largely reactive rather than predictive. 4. Professor Rose then pioneered QMRA in the 1990s and early 2000s to address these critical gaps undermining water safety and public health. QMRA introduced a systematic, science-based approach to assess and manage microbial risks in drinking and other forms of water, including reuse water. By enabling scientists to quantify infection risks and illness probabilities based on pathogen concentrations, exposure pathways and consumption patterns, QMRA shifted water management from reactive "detect and correct" approaches to proactive "predict and prevent" strategies. This revolutionised water safety, boosting the quality of water systems to reliably meet health standards. Global impact on water microbiology and water quality 5. QMRA is now widely adopted in drinking water regulations worldwide including the United States Environmental Protection Agency's Safe Drinking Water Standards and the World Health Organisation's Third Edition of the Drinking Water Quality Guidelines in 2004. Her work has enabled water utilities and regulators to define treatment requirements based on tolerable health risks for any given water source. 6. Professor Rose extended the application of QMRA beyond drinking water to assess microbial risks in treated wastewater and water reuse systems. This development greatly strengthened global confidence in leveraging recycled water as a viable and sustainable supply source, and Professor Rose has since strongly advocated for the adoption of water reuse to address global water scarcity. She also advised the Orange County Water District's Independent Advisory Panel and the California State Water Resources Control Board's Expert Panel on water reuse. Her guidance contributed to California's Indirect and Direct Potable Reuse regulations, now models for water reuse standards worldwide, including in Australia, Spain, and the United States. 7. For over two decades, Professor Rose worked closely with PUB, Singapore's National Water Agency, to strengthen water quality and safety. She was...
