Adenoviruses are important human pathogens that are responsible for both enteric illnesses and respiratory and eye infections. Recently, these viruses have been found to be prevalent in rivers, coastal waters, swimming pool waters, and drinking water supplies worldwide. United Sates Environmental Protection Agency (USEPA) listed adenovirus as one of nine microorganisms on the Contamination Candidate List for drinking water because their survival characteristic during water treatment is not yet fully understood. Adenoviruses have been found to be significantly more stable than fecal indicator bacteria and other enteric viruses during UV treatment. Adenovirus infection may be caused by consumption of contaminated water or inhalation of aerosolized droplets during water recreation. The goal of this review is to summarize the state of technology for adenovirus detection in natural and drinking waters and the human health risk imposed by this emerging pathogen. The occurrence of these viruses in natural and treated waters is summarized from worldwide reports.