The proposed research develops and examines the efficiency of a novel molecular technique for identification and quantification of waterborne pathogens. A novel view of virulence genes as biomarkers for pathogenic species is proposed and could enable effective molecular quantification of pathogens in water samples. If successful, this study could develop an approach for applying molecular techniques as routine drinking water monitoring tools, and enabling the generation of quantitative data, that is necessary for assessing potential health threats. It is also expected that a new form of dose-response relationship, expressed as copies of virulence genes vs. health risk, will be developed.