Background: Water is essential for supporting public health and life without water is impossible. Microbial guidelines seek to ensure that drinking water is free of microorganisms that can cause disease. Objectives: This study focused on examination of drinking water (100 samples) from different community water supplies in Tanta city, Egypt for bacterial contamination and relationship between drinking water and gastrointestinal manifestations. Methodology: Drinking water samples were collected from different sources and places and subjected to three tests: a) measurement of physical characters of water pH, turbidity and free residual chlorine b) heterotrophic bacterial count technique c) multiple tube fermentation technique for identification of E.Coli and Strept faecalis. Results: Samples conformed to standard specifications bacteriologically and physically were 80% and 90% respectively. Samples with abnormal pH, turbidity and free residual chlorine were 2%, 8% and 14% of respectively. The incidence of total coliforms, E.Coli and Strept faecalis was 17%, 5% and 2% respectively. Attacks of GIT manifestations were present in people in 20% of places. Abnormal turbidity >1 NTU was significant with total coliforms. Total coliforms ≥2.2, abnormal turbidity >1 NTU and heterotrophic bacterial count >500 at 37ºC were significant with attacks of gastrointestinal manifestations. Conclusion: Ground water better than filtered water and less liable to microbial contamination. Turbidity is a good indicator for total coliforms and is significant with attacks of GIT manifestations. Use of water filters (7 stages) in all houses is recommended for improvement of water criteria.