The problem of water pollution in Biskra (South-eastern Algeria) is a subject that remains unsolved despite several initiations undertaken to the current date. Our study focuses initially on the characterization and seasonal evolution of bacteriological pollution parameters of the three major releases of Biskra city named as follow: Chabat Roba (site1) Messdour (site2) and Oued Z'ommor (site3). According to our results, it appears that the pollution load in site 1 is about 9.30 x 106 ± 6.66 x 106 germs / ml for total germs and 5.48 x 104 ± 2.98 x 104 germs / ml for E. coli. Regarding site 2 the pollution load is represented by 10.79 x 106 ± 8.04 x 106 germs / ml of total germs and 6.07 x 104 ± 3.31 x 104 germs / ml of E. coli. Concerning Site 3 the pollution load is 10.93 x 106 ± 8.83 x 106 germs / ml for total germs and 4.98 x 104 ± 2.34 x 104 germs / ml for E. coli. In fact bacteriological monitoring carried out confirms the presence of fecal contamination (fecal coliforms, E. coli, faecal streptococci and sulphite-decreasing clostridia) and also pathogenic (presence of Shigella).