Water is an essential aspect of life and important in evolution. Recently the potable water quality topic has received much attention. The study aims to determine drinking water quality in Al-Najaf City by collecting samples throughout Al-Najaf city and comparing the results with the Iraqi guidelines (IQS 417) and World Health Organization (WHO) guidelines, as well as to calculate the WQI. Samples were tested in the laboratory between December 2021 and June 2022. The results showed that multiple parameters exceeded the allowable limits during both testing periods; during winter months, the results of TDS and turbidity exceeded the upper limits in multiple locations. Total hardness values also exceeded the limit of 500 ppm for all samples taken in the winter period. For magnesium and calcium, summer measurements were mainly within limits, unlike winter period measurements which mostly exceeded the limits. Residual chlorine tests in winter had higher concentrations, generally ranging from 0.25 to 0.8 mg/l. While During summer, concentrations dropped below the allowable limit in multiple sampling points. The study concluded that the majority of the water samples gathered during the winter months were of poor quality as the total WQI values were between (99-110), While the total WQI values for water samples collected during the summer period were rated as good quality water ranged between (75-81).
