The study aimed to determine the temporal and spatial hydrochemical changes in the Euphrates River’s monitoring stations and groundwater in Al-Najaf city, Iraq, to assess their suitability for drinking and domestic use. Water samples were collected monthly from E11, E13 and Eab stations and one groundwater source, from January to December 2017. The results showed no significant differences (p < 0.05) for pH, Temperature, Turbidity and PO4−3. However, significant differences were observed for other physicochemical parameters. Additionally, hydrochemical characteristics were determined using geochemical methods. The water from Euphrates River resources was characterised as weakly alkaline and excessively hard. The predominance of major cations in Euphrates River’s water, according to Schoeller’s diagram, was in the following order: Ca+2 > Na+ > Mg++ > K+. The predominant anions were as follows: SO4−2 > Cl− > HCO3− > NO3−. The hydrochemical process resulted in a Ca-SO4 water type for Euphrates River, primarily influenced by water-rock interactions and the dissolution of carbonates. The water was supersaturated according to the saturation index (SI > 0) with respect to dolomite > calcite > aragonite > magnesite, while it was unsaturated (SI < 0) with respect to gypsum, halite and anhydrite. Most indicators met the permissible limits for drinking water, except for turbidity, oil & grease, biochemical oxygen demand and chemical oxygen demand. These factors should be considered when designing treatment or purification plants for domestic use. The well water was classified as saline and unsuitable for drinking or domestic purposes.