Water is one of the most abundant and essential commodities of man occupying about 70% of the earth's surface and 60% of the human body therefore it should be continuously protected against microbial infections. Also, the mineral content in drinking water should be maintained within the acceptable range. Quality control of drinking water emerged with the invention of bottled drinking water. In this study, samples of bottled drinking water from Saudi markets were compared with tap water samples collected from different areas in Riyadh; both samples were tested for the presence of pathogenic bacteria. The bacterial isolates identified by the Biolog system (Hayward, CA, USA) include Bacillus cereus, Staphylococcus sp. and Pseudomonas aeruginosa in bottled drinking water, whereas tap water was mainly contaminated by P. aeruginosa. Bacterial contamination was highly observed in tap water samples and higher mineral content, determined by inductively coupled plasma-mass spectrometry (ICP-MS) was also observed in tap water. Bacterial cell count determined as CFU/ml was observed in bottled drinking water. Decreased water bacterial number was achieved with the solar disinfection system (SODIS) for one day with direct exposure to sunlight in polyethylene terephthalate (PET) plastic bottles. Thus water considered to be consumed by humans must maintain good microbial and mineral qualities within the acceptable ranges and must undergo effective treatment in order to reduce bacterial count and infection.