The UV radiations have become an effectiveway for the sake of solving all problems related to environmental contamination. An example of that is their use in the field ofwater treatment. The effectiveness ofUVin inhibiting the growth of pathogens can be seen in several case studies. This inspiration led us to choose the UV and see their degree of implication on our pathogenic microorganisms (of ourmicro- library). Tomaterialize this, we propose monitoring the effect of the time and distance of exposure factors on the control microbial growth. In addition, it is good for us to determine the minimuminhibitory time (MIT) and the minimumexposure distance (MED) on each bacterial type. Tests are carried on the followingmicroorganisms:Klebsiella pneumoniae, Staphylococcus aureus, Pseudomonas aeruginosae, Escherichia coli, Enterobacter cloacae and Proteus mirabilis. The cultures were irradiated withUV. The selected distances are 3 and 13 cmand the exposure time was 10min, 20min, 30min, 40min and 50min.All treatments are carried out in a dark chamber. Further, the control group is prepared in the same conditions. The extermination of most microorganisms has been viewed due to the combined effect of time and the exposure distance. The time of 40min and a distance of 3 cm was the best combination to achieve the total cessation of growth of the bacteria studied.