Urban water sources of Khamis Mushayt Governorate, southwestern Saudi Arabia, were studied to assess their bacteriological characteristics and suitability for potable purposes. A cross-sectional epidemiological method was adopted to investigate the four main urban water sources (i.e. bottled, desalinated, surface, and well water). These were sampled and examined between February and June 2007. After a series of tests, it was found out that water derived from traditional sources (wells) showed increases in most of the investigated bacteriological parameters, followed by surface water as compared to bottled or desalinated water. This may be attributed to the fact that well and surface water are at risk of contamination as indicated by the higher levels of most bacteriological parameters. Moreover, well water is exposed to point sources of pollution such as septic wells and domestic and farming effluents, as well as to soil with a high humus content. The lower bacteriological characteristics in samples from bottled water indicate that it is satisfactory for human drinking purposes. Contamination of desalinated water that is the main urban water source may occur during transportation from the desalination plant or in the house reservoir of the consumer. Improving and expanding the existing water treatment and sanitation systems is more likely to provide safe and sustainable sources of water over the long term. Strict hygienic measures should be applied to improve water quality and to avoid deleterious effects on public health, by using periodical monitoring programs to detect sewage pollution running over local hydrological networks and valleys. A total of 95 water samples from bottled, desalinated, surface, and well water were collected randomly from the study area using different gathering and analyzing techniques. The bacteriological examination of water samples included the most probable number of presumptive coliforms, faecal coliforms, and faecal streptococci (MPN/ 100 ml). The results showed that the total coliform count (MPN/100 ml) was not detected in any samples taken from bottled water, while it was detected in those taken from desalinated, surface, and well water: percentages were 12.9, 80.0, and 100.0, respectively. Faecal coliforms were detected in desalinated, surface, and well water.
