The objective of this study is to assess the physical-chemical quality of urban wastewater from the city of Boumerdès, in northern Algeria with regard to the threshold values for irrigation or their discharge in aquatic ecosystems. Five sampling points were carried out of the study area in April 2017. The results obtained of physical- chemical parameters indicating pollution show that the water course is exposed to pollution mainly of organic origin. It’s expressed by a high maximum value according to Algerian and World Health Organisation standards: chemical oxygen demand ( COD 886 mg O ₂∙dm ^–3), biochemical oxygen demand ( BOD ₅ 490 mg O2∙dm ^–3), nitrate (NO ₃ ^– 73.09 mg∙dm ^–3), nitrite (NO ₂ ^–6 mg∙dm ^–3), ammonium (NH ₄ ⁺ 23 mg∙dm ^–3) and phosphates (PO ₄ ^3– 7.3 mg∙dm ^–3). The COD to BOD ₅ rate of 1.8, show that the effluents must be treated before being discharged into the receiving environment. However, it is lower than 2, which makes them easily biodegradable and can be treated by a biological system such as a natural lagoon. It shows also a diversified origin of the pollution. It is predominantly domestic origin, it could have an adverse effect on public health, presenting a risk of environmental eutrophication, contamination of soil and water resources. The physical-chemical characterisation of the urban wastewater shows that they are quite loaded and present a pollution in nitrogenous compounds, a treatment is requested before the direct discharge to the receiving environment or their reuse in the irrigation.