The public health of developing and undeveloped countries is in crisis due to an increased incidence of acute gastroenteritis via contaminated drinking water. Acute gastroenteritis is the third leading cause of mortality in the world. According to the World Health Organization, there were estimates of 4 billion cases of diarrhea and 2.2 million deaths annually in these countries due to consumption of unsafe drinking water. Generally, most acute gastroenteritis pathogens are transmitted via contaminated food, but waterborne transmission has been well documented for recreational and contaminated drinking water. Usually, gastroenteritis which is caused by poor sanitation and by contaminated water is part of those diseases in developing countries. Inadequate and unsafe drinking water supplies are continuing public health problems for most of the world's populations. The objective of this chapter is an attempt to determine the role of bacterial agents in acute gastroenteritis via drinking water in developing countries.