In the present work, an estimation of alpha - emitters concentration in water in Baghdad City is measured using CR-39 plastic track detector. The study covers the water refinement projects on Tigris river in the city. Two methods were employed: the natural exposure method which included immersing the detectors directly in the water samples and leaving them for different periods (5, 10, 30, 50 and 70 days), and the neutron activation method using fission fragments tracks registration. The nuclear reaction used as a source of nuclear fission fragments is U-235 (n , f) obtained by the bombardment of U-235 with thermal neutrons from Am-Be neutron source which has a flux of 5000 n.cm-².s-1. The concentration values were calculated by comparison with standard (Urinal acetate) prepared with different concentrations (1, 2.5, 5, 15, 25, 50, 100, 150 and 200). The results obtained show that no significant change in the alpha – emitters concentrations with the exposure time periods. In comparison with the EPA standards of drinking water, the present results demonstrate that there are three contaminated sites, which are S3, S5 and S7 respectively. The minimum alpha - emitters concentration were in the sites S3, S6 and S7 respectively. The fractional difference in alpha – emitters concentration prior to and after the refinement process (i.e. refinement efficiency) was determined. The better water refinement efficiency was in the projects S4 and S9. For irradiation method the results were in good agreement (within the experimental error) with that obtained in the natural exposure method for both the concentrations and efficiency of each refinement project. The present work demonstrates that the radioactive contamination in drinking water supplied from one-third of the refinement projects can be redused by increasing the refinement efficiency of these projects. Despite the absence of prerion works related to the investigated sites, the radioactive contamination due to the USA forces use of nuclear wastes in weapons against Iraq in 1991 cannot be excluded.