Rn-222 measurements in water samples collected from 27 wells and 19 taps that were supplied from the investigated wells were conducted using the AlphaGUARD PQ 2000PRO radon gas analyser at sites across several geologic formations within the city of Bursa, Turkey. The measured radon concentrations ranged from 1.46 to 53.64 Bq l(1) for well water and from 0.91 to 12.58 Bq l(1) for tap water. Of the 27 sites sampled, only 7 had radon levels above the safe limit of 11.1 Bq l(1) recommended by the USEPA. In general, all determined concentrations were well below the 100 Bq l(1) revised reference level proposed by the European Union. These values of radon concentrations in water samples are compared with those reported from other countries. Doses resulting from the consumption of these waters were calculated. The minimum and the maximum annual mean effective doses due to Rn-222 intake through water consumption were 0.02 Sv a(1) and 1.11 Sv a(1), respectively.