Science and Education Publishing International Journal of Physics 2333-4576 4 5 2016 8 6 Measurement of Radon Gas Concentration in Tap Water Samples in Wassit Governorate by Using Nuclear Track Detector (CR-39) 119 122 EN Laith Ahmed Najam Department of Physics, College of Science, University of Mosul, Mosul, Iraq Mahmood Salim Karim Taghreed Khalid Hameed IJP2016451 10.12691/ijp-4-5-1 2016 2 17 2016 6 30 2016 8 4 In the present work, we have measured the radon gas concentration in environmental water sample of selected regions in Wassit governorate by using alpha-emitters registrations which are emitted from radon gas in (CR-39) nuclear track detector. The results of measurements indicate that the highest average radon gas concentrations in tap water samples were found in Nuamaniya region, which was equal to (0.820±0.04 Bq/L), while the lowest average radon gas concentration was found in Jassan region, which was equal to (0.325±0.02 Bq/L), with an average value of (0.563±0.12Bq/L). The highest value of annual effective dose (AED) in tap water samples was found in Nuamaniya region, which was equal to (0.08 μSv/y), while the lowest value of annual effective dose (AED) was found in Jassan region, which was equal to (0.03μSv /y), with an average value of (0.05±0.01 ̦Sv/y), the tap water in Wassit governorate is safe as far as radon concentration is concerned.