Dissolved radon (222Rn) in drinking water has been measured using SMART RnDuo, a continuous radon monitor. Water samples have been collected from hand pumps in surrounding regions of a Harduaganj thermal power plant (HTPP), Aligarh and Narora atomic power plant (NAPP), Bulandshahar situated in the Uttar Pradesh state of India. The 222Rn concentration ranges from 1.3 ± 0.3 to 17 ± 1 Bql−1 around HTPP, and from 2.4 ± 0.5 to 17 ± 1 Bql−1 around NAPP. The measured radon concentration in all collected samples lies well below the limit of 100 Bql−1as set by the World Health Organization. The total annual effective dose due to waterborne 222Rn inhalation and ingestion varies from 6 ± 1 to 88 ± 4 μSvy−1 around HTPP and from 6 ± 1 to 42 ± 3 μSvy−1 around NAPP. The total annual effective dose around both the plants is also well below the safe limit of 100 μSvy−1 recommended by the European Commission and World Health Organization. The radiation dose to the lungs, stomach, and liver are also calculated in the regions under study.