This research work aimed to investigate the degree of quality of tap and bottled waters available in Al-Madinah city through an experimental program comprising chemical, physical and biological tests. The study included examining the quality of the water supply network components such as taps, underground storage tanks and feeding pipes of the network. Filtration influence on the tap water was investigated by testing different water samples before and after the filtration process at different locations. The experiments also examined various bottled water brands sold in Al-Madinah. In addition, the impact of using the dispenser on the water quality of large bottled waters was studied. The water quality of two types of waters was compared by estimating water quality index (WQI). Results of this study revealed that the overall quality of the tap water is within standard values; however, deterioration occurs for the water through its journey in the water supply system. Results revealed that hardness and fluoride concentrations in bottled waters exhibited high values close to or more than allowable values of the standards. Furthermore, results confirmed that using the filter and dispenser decreased the water quality degree in the long run. Bottled waters showed a higher grade of WQI than tap water.