Libya is a country of desert and the arid climate makes it in extreme lack of surface water. Groundwater then becomes a very important resource to meet the economical and agricultural demand, which believed to be comparatively much cleaner and free from pollution than surface water. Water pollution is a state of deviation from pure condition, whereby its normal function and properties are affected. The present study is aimed at assesses the bacteriological pollution of ground water samples used for humans and animals at different 11 localities in Tripoli region, Libya. This study related to the bacteriological analysis revealed high values of total bacterial count in groundwater samples from both tanks (648.85 cfu /ml) and wells (349.34 cfu /ml) than standard count limit (100 cfu /ml) for drinking water by EPA. Nearly similar values of MPN of coliform (58.00 MPN/100 ml) and E. coli bacteria (0.20) from both tanks and wells, other than zero number per 100 ml set by WHO. Finally, we did not find pathogenic bacteria; as Salmonella and Enterococci bacteria, but there is very little number of pathogenic bacteria as Staphylococcus aurous (1.50) and Pseudomonas aeruginosa (0.07) isolated from both tanks and wells samples. Hence, it was concluded that, this research to analysis the bacteriological pollution of groundwater used for humans and animals at some different localities of Tripoli, Libya with review to the hygienic standards and suggest an approach for improving and prevent such contamination. microbiological tested ground waters samples are good and mostly suitable for domestic uses, the coliform and pathogenic bacterial contamination render this water unsatisfactory for drinking purposes unless bacteriologically perfectly treated, if necessary for consideration for utility.