QMRA for assessing treatment needs of surface water for drinking: trends and challenges in fecal pathogen quantification.

Pathogens are widespread in surface waters, necessitating effective microbial removal by drinking water treatment systems to ensure public health. Quantitative microbial risk assessment (QMRA) provides a robust framework to estimate required pathogen reduction by integrating source water pathogen levels with acceptable health risk thresholds. Accurate quantification of pathogen loads is a critical first step in QMRA. This review provides a comprehensive overview of methods for quantifying fecal pathogen loads in surface waters for QMRA applications. We conducted an extensive literature review to identify the most commonly targeted fecal pathogens and the quantification strategies used, including approaches that measure the pathogens directly and indirect approaches that use surrogate indicators of fecal contamination. The applicability, strengths, and limitations of these methods are critically evaluated. This review guides QMRA in surface waters toward more reliable and appropriate risk assessments to support safe drinking water goals.