Surveys of radon levels in air have been carried out throughout Europe to determine the magnitude of average exposures and to identify situations where excessive exposures occur. At present, specialists can use several types of apparatus based on different detectors, for measuring radon in air and providing spot, integrated or continuous measurements. In contrast, there are few techniques for measuring radon in water, and practically none provide continuous measurements in this medium and a very few works have been carried out. The proposed project involves the development of a real time, automated and continuous radon detection in water, monitoring and alarming system under full computer Supervision. It will be efficiently used either after site remediation or as a warning system on endangered, or potentially to be contaminated sites.