The presence of radon in drinking water causes health risks associated with exposure from both inhalation and ingestion. Since the studies show that faults near the water resources have a critical effect on the concentration of radon, Kouhbanan active fault zone, to find water resources with high radon concentration was chosen for the following investigation. Water samples were taken from all of the 39 drinking water springs and Qanats in the Kouhbanan region, both in the summer and winter. Its length is 280Km and is aligned from Bahabad city in north-west to the Kerman city in south-east. Some evidence of the activity of this fault system are young morphotectonic structures and earthquake events along of this faults. To determine the content of sample’s radon, radon detector (RAD7) was used. In six out of water samples, radon levels was more than proposed emission 11.1kbm-3(MCL) by Environmental Protection Agency (EPA). The average annual effective dose in 2 regions is more than reference level of the European Union Council and world health organization (0. 1mSva-1) according to the average effective dose for ingestion of radon in water (0.002mSva-1) and inhalation (0.025mSva-1) by United Nations Scientific Committee on the Effective of Atomic Radiations. This study has concluded that the mean effective dose for ingestion and inhalation of radon in Kouhbanan fault zone, is greater than the amount recommended for water samples in 6 region.