The main objective of this study was to evaluate the contribution of activated carbon, based on coconut shell, in the treatment of mangrove and well contaminated water from the BONAPRISO district. More precisely, it consisted of preparing the activated carbon, then characterizing the mangrove water and the well water through a manual of sampling procedure; and finally verifying that the activated carbon produced had a good capacity for absorption of bacteria contained in the different sampled waters. Therefore, it emerged from this study that the activated carbon produced from coconut pods carbonized at 561°C, ground and activated at 443°C, had a specific surface of 658 m 2 /g and pore sizes of 20 µm. Thereafter the various waters characterized showed a yellowish coloration for well water and whitish for mangrove water, a pH ranging from 6.5 and 6.8, respectively; and the total flora had a total load of 2.18×10 5 CFU/ml for well water and a total load of 3.24×10 5 CFU/ml for mangrove water. Finally, the effectiveness of activated carbon in fixing bacteria, such as total flora, streptococci, and faecal coliforms showed that it was adsorbed in well water: 86.45% total flora; 91.67% streptococci; 100% faecal coliforms, and therefore, acted at 92.7%. Similarly, in mangrove water, there is 51.22% of total flora, 100% streptococci, and 92.4% faecal coliforms were fixed and, therefore, acted at 81.20%. The remaining bacteria, in well water (13.55% total flora; 8.33% streptococci) and in mangrove water (48.78% total flora; 7.6% faecal coliforms), respectively, could not be fixed.