A Comparative analysis of the bacteriological quality of water supply sources was carried out. The study involved the determination of the faecal coliform count and residual chlorine concentrations of water samples in accordance with the steps laid down in Standard Methods (APHA 1990). It also involved the determination of the incidence of diarrhoeal diseases among water consumers using the medical records of patients attending the school clinic and with the use of questionnaires administered on 300 respondents randomly selected from among staff and students using stratified sampling technique. Generally, the result showed that all the water samples were heavily contaminated. A minimum coliform count of 1×102 was determined for tap water at the treatment site and the maximum count of 8×102 was recorded at a distance of 2km from the treatment site. None of the water supply sources (well, tap water, and bore hole) available to the residents meets the standard set by World Health organisation (WHO) for drinking water which states that “Drinking water must be free from microbial contamination and the coliform count must be zero or less than I per l00mls of treated water” (WHO 1972). The high coliform counts of tap water samples may have resulted from the inadequate treatment of water observed at the treatment plant and the possibility of additional pollution within the distribution system. It was observed that the heavy contamination of well water supplies are likely due to improper construction and poor protection of the wells. In addition, the poor drainage and waste disposal pattern of the vii campus which frequently leads to flooding during rainy season may have contributed to well water contamination from sewage and animal wastes. The findings also revealed that the residual chlorine levels diminishes as water flows away from the treatment plant with a corresponding increase in faecal coliform counts. Hence the residual chlorine concentrations persistently failed to meet the standard requirement of l.0mg/L at the treatment plant and 0.2mg/L in the distribution system (Freedmen 1977). These finding compare well with previously published Data (Buelow and Walton, 1970, White, 1975, Yusuf, 1983). A high incidence of diarrhoeal diseases was observed in the study especially during the months of July and August at the peak of rainy season with majority (61.4%) occurring in children under 3 years of age. Only 4 % of the respondents, were found to be treating their water before consumption despite the fact that a significant proportion (58 or 19%) of these respondents source water from both wells and tap. The importance of water availability as the most important factor in the control of morbidity and mortality from diarrhoeal diseases has been highlighted in other studies ( Watt et al, 1966, WHO, 1969, Osuhoretal, 1978, Essien, 1980, WHO,1987). The X2 test done to determine whether there is a significant relationship between the incidence of diarrhoea diseases and the type of water sources used for drinking purposes revealed a strong association between water pollution and diarrhoeal diseases. This finding is similar to previously published work in which socio-demographic factors including the quality of water supplies and availability of good latrines were found to be associated with the incidence of diarrhoeal diseases in developing countries (Essien 1980; Stanton and Clemens 1987; Young and Brisco 1988). Education and health messages were also recommended for the improvement of available water supply sources.