Objective: This study was aimed to determine the seasonal distribution and antimicrobial resistance of Gram negative bacteria isolated from Adana-Tufanbeyli road line tap water.

Materials and Methods: The susceptibilities of 269 Gram-negative bacterial isolates to13 different antimicrobial agents were investigated by agar diffusion method.

Results: The most common strains isolated from all samples were Proteus vulgaris (44.5%). followed by Escherichia coli (25.6%), Pseudomonas aeruginosa (18.9%) and Citrobacter species (10.4%). There was a high rate of resistance to cephalothin (68.6%) and ampicillin (52.1%), and a low rate of resistance to amikacin (0.95%) gentamicin (%1.2) and tobramicin (%2.5). Multiple antibiotic resistance index values ranged from 0.23 to 0.69.

Conclusion: Adana-Tufanbeyli road line tap water contaminated important level of resistant microorganisms which were caused serious health problem was the conclusion of this study.