All kinds of life, including people, animals, plants, and other species, depend on the rich natural resources of water. However, this valuable resource is becoming increasingly threatened by the increasing population as well as the growing demand for quality water for domestic and economic purposes. Hence the requirement for ongoing river water quality monitoring and assessment. In this research, the water quality (WQ) of the Al-Abbasiyah River was assessed for drinking uses in the dry and wet seasons using the weighted arithmetic water quality index (WAWQI) and GIS software. Eighteen physical, chemical, and biological parameters were measured in 2022 (dry season) and 2023 (wet season) by collecting samples from eight locations along the river. These parameters are: Temperature, EC, pH, TDS, TSS, Turbidity, DO, BOD5, alkalinity, NO3-, HCO3-, Cl-, Mg+2, Ca+2, Na+, K+, TH, and SO4-2. The average of the measured water parameters showed that some of these parameters exceeded the standards limit of the WHO in all locations such as (Alk, TH, Ca+2, Mg+2, SO4-2) and at some locations such as (TDS, Turbidity, and HCO3-). During the dry season, the WA-WQI values varied between 70.33 in (L-4) within the category of "Poor" and 119.87 in (L-7) within the category of "Unsuitable", while in the wet season varied between 49.71 in (L-5) within the category of "Good", and 79.35 in (L-2) within the category of “Poor”. Thus, the water of the Al-Abbasiyah River was unfit for drinking directly and must undergo treatment before use in both seasons.