Water samples collected from different sources were analysed for radon concentrations in order to evaluate the health effect associated with radon in water. The radon concentrations were in the range of 3.56–98.57, 0.88–25.49, 0.73–1.35 and 0.24–1.03 Bq.L−1 for borehole, well, packaged and utility water, respectively. Samples from boreholes had the highest radon concentrations with about 67% being higher than the threshold value of 11.1 Bq.L−1 recommended by the USEPA. The mean annual effective dose (AED) due to ingestion for adult, child and infant ranged from 8.71 × 10−3 to 0.831 mSv.y−1 for the different sources. The mean AED calculated for consuming water from boreholes and wells for the three age groups were higher than the recommended reference dose level of 0.1 mSv.y−1. The mean AED due to inhalation of radon in drinking water was negligible, ranging from 0.13 to 6.20 μSv.y−1. The health burden associated with radon in water in the study is through ingestion of water directly from boreholes.