Sanitation services play a critical role in controlling transmission of numerous waterborne pathogens, especially viruses that cause acute gastroenteritis and hepatitis. The viral agents with the greatest public health impact are hepatitis A virus, rotaviruses and noroviruses, adenoviruses, and enteroviruses, contaminating many Brazilian aquatic ecosystems. Heavy circulation of viruses in the environment has been related to inadequate local sanitary conditions, including incomplete coverage of services or inefficacy of conventional technologies in eliminating or reducing the viral load in water or sewage. This study reviews the relations between virology, health, and sanitation, emphasizing the epidemiology of waterborne viral infections and their public health impact.