The paper characterises the method of estimating the size of the areas supplying radon to radon groundwater intakes. It is presented on the example of the intakes of radon groundwaters and radon acidulous waters of Lądek Zdrój, Świeradów Zdrój and Kowary. The results of appropriate calculations prove that the volume of rocks supplying radon to the groundwaters of particular intakes oscillates from over ten to several hundred thousand cubic metres. Considering the depth of the zone where radon saturation of these waters takes place, the area supplying this gas to particular intakes varies from several hundred to several thousand square metres. The largest areas of radon-222 supply are characteristic of the most discharge springs, while the smallest ones belong to the springs of low discharge, especially the intakes of groundwater mixture, where only one component supplies large quantities of radon-222. The recharge areas of groundwaters in which