Groundwater is the most valuable resource in arid regions, and recognizing radiological criteria among other water quality parameters is essential for sustainable use. In the investigation presented here, gross-alpha and gross-beta were measured in groundwater samples collected in the south-eastern Arabian Peninsula, 67 wells in Unite Arab Emirates (UAE), as well as two wells and one spring in Oman. The results show a wide gross-alpha and gross-beta activities range in the groundwater samples that vary at 0.01 similar to 19.5 Bq/l and 0.13 similar to 6.6 Bq/l, respectively. The data show gross-beta and gross-alpha values below the WHO permissible limits for drinking water in the majority of the investigated samples except those in region 4 (Jabel Hafit and surroundings). No correlation between groundwater pH and the gross-alpha and gross-beta, while high temperatures probably enhance leaching of radionuclides from the aquifer body and thereby increase the radioactivity in the groundwater. This conclusion is also supported by the positive correlation between radioactivity and amount of total dissolved solid. Particular water purification technology and environmental impact assessments are essential for sustainable and secure use of the groundwater in regions that show radioactivity values far above the WHO permissible limit for drinking water.