The microbial contamination of ground water is a serious problem that can result in large outbreaks of waterborne disease. The purpose of this article is to review the literature available on viruses in ground water in order to evaluate the present state-of-knowledge, assess the accuracy of current standards and monitoring practices, and make recommendations for further areas of research. Reports on virus isolation from various ground-water sources are discussed with an emphasis being placed on land treatment sites. When effectively operated, land treatment can reduce viruses to a level that is achieved only with costly advanced wastewater treatment and disinfection.