This study was made to comprehend the effects of human behaviour on bacteriological quality of drinking water consumed by the population of Sô-Ava and to identify the possible environment factors that deteriorate the quality of water. Thirty samples of water were collected in different ways, during rainy season and dry season for bacteriological examination. To identify the environmental factors, 165 couples were questioned. The results recorded showed that during dry season the amounts of germs were within WHO safety limits for each and every sampling station while during rainy season the results highly exceeded the safety limits. The isolation of germs like total coliforms, faecal coliforms, "Escherichia coli" and "Clostridium perfringens" revealed a faecal pollution. The presence of pathogens like "Staphylococcus", "Salmonella" and "Shigella" in surface water constituted a threat for the groundwater. The factors responsible for these contaminations were many and were mainly related to hygienic condition and sanitation according to the opinion poll. The improvement of health for the population of So- Ava implies-in addition to improving the quality of water, hygiene and sanitation and appropriate environment management of the town.