The aim of this study is to assess the pollutant load of effluents drained into the sewerage system of the city of Abidjan. Between 2020 and 2023, three sampling campaigns per year were carried out to monitor these waters. A total of 144 wastewater samples were collected and analysed in the laboratory in accordance with the standards in force at the Sub-Directorate for the Inspection of Classified Installations (SDIIC). Parameters such as BOD5, COD, MES, NH4+, NTK, PO43-, NO2-, NO3-, T°C and pH were measured. A multivariate statistical analysis identified the origin of these effluents in the network. The pH varied greatly from very acidic 3.1 to strongly alkaline 13.6. The average values obtained were 292.0 mg/L; 60.9 mg/L and 82.0 mg/L respectively for MES, NH4+ and NTK, with limit values of 150 mg/L, 15 mg/L and 50 mg/L. The COD and BOD5 concentrations were 1232.1 mgO2/L and 374.9 mgO2/L respectively. The limit values for these parameters are 500 mgO2/L and 150 mgO2/L. The COD/BOD5 ratio varies from 2.6 to 4.8, while the BOD5/COD ratio is between 0.30 and 0.46. These values indicate non-biodegradable effluents. Multivariate analysis indicates that the effluents drained by the network are of industrial origin or predominantly industrial. The non-biodegradability of these effluents, which are often discharged into the Ebrié lagoon without any pre-treatment, poses an environmental risk to this natural receptacle.