The percolation of the leachate from the waste from landfills is a source of pollution of the groundwater resources by infiltration, thus constituting a threat as important as the one linked to the enhancement of the water deficit. The measures carried out on the leachate from the landfill of Ouled Berjel (Kenitra) and having door on bacteriological analyzes, allow you to qualify the leachate as a source of contamination to potential anoxic and reducer. The results of the bacteriological characterization indicated a very poor microbiological quality of leachate. Indeed, higher 2,43.107 ufc / ml rate, leachate were recorded for total coliforms and faecal coliforms, considered tracers forefront of microbial pollution in landfills juice. What makes these highly toxic effluents and thus have a permanent danger to the health of the local population and the surrounding environment, and therefore require a specific treatment before being discharged into the receiving environment.