Abstract
Ramsar is one of the highest background radiation areas in the world, whose natural radioactivity is due to 238U natural series and its decay products, especially 226Ra and 220Rn, which have been brought to the surface by water of hot springs. In this study, radon concentration in 14 drinking water sources of the Ramsar region has been measured with the PRASSI system. The results show all of the water supplies have radon concentration greater than 10kBq/m3 as normal level. Moreover, the estimated mean annual radiation dose to public due to waterborne radon has also been evaluated.