Escherichia coliO157:H7 is a zoonotic pathogen with its ability to cause human illness ranging from diarrheal dis-ease to fatal hemolytic uremic syndrome.E. coliO157:H7 had been associated with waterborne outbreaksresulting in high morbidity and mortality worldwide. Therefore, it is important to investigate the prevalence ofE. coliO157:H7 in water sources especially used for drinking and to develop the diagnostic methods for itsearly detection. The review describes traditional cultural methods, immunological techniques, and polymerasechain reaction (PCR)–based methods for detection of this bacterium in water sources. The current PCR-basedtechniques such as real-time PCR are more specific and sensitive and require less detection time (b3 hours).These methods can be applied for regular water monitoring and proper management of water sources to preventwaterborne diseases due toE. coliO157:H7.