The city of Mosul contains a single water source, which represents the main artery of this city, namely the Tigris River. It was necessary to study and evaluate the quality of water, especially in the Rashidieh area since it represents the beginning of the entry of the Tigris River from the northern region, as well as addressing the extent of pollution in it and the extent of water susceptibility to self-purification.Water samples were collected from the Rashidieh area, and five sites were selected along the course of the Tigris River passing within that area. The results of the  current study showed that the average temperature ranged between 10.25-14.25°C, and some indicators were measured and the highest value of the pH function was recorded (2.4) at the second site and the lowest value was recorded (0.08) at site 5. Moreover, the average values of TDS, DO, T.H, PO3³⁻, NO3^-  and Cl^- ranged from 253.7–338.7, 5.29-8.46,115.6-254.8, 0.248–5.26, 1.73-18.08, and 30.5–56mg/l, respectively, and most of the values were within the permissible limits and fall within the Iraqi and international standards, except for the acid function, dissolved oxygen and phosphate that recorded values exceeding the permissible limits, especially in the Rashidiya estuary area, the second site, which greatly and significantly affected the Tigris River. Therefore, the sites were classified based on the values of the Canadian index, and the values ranged from good for the Tigris River to poor quality for the Rashidiya estuary and questionable for site 3, while site 4 and 5 were classified as acceptable, and thus the ability of the Tigris River to self-purify was not at the required level.