A Survey of Raduim 226 level in 111 water supply samples of Amphur Meaung Khonkaen were determined by measuring Radium 226 via Manganese Fibers using gamma spectrometry. The average of 226Ra was found to be 0.038 Bq/l, range 0 – 0.13 Bq/l. The average risk of Annual Equivalent Dose was found to be 0.023 mSv/l, range 0 – 0.079 mSv/y. This study show that 226Ra in water supply of Amphur Muang Khonkhean is not more than 0.11 Bq/l which is the standard value of the United States Environmental Protection Agency, and its Annual Equivalent Dose does not exceed 0.1 mSv/y which is the maximum dose for the public water. Therefore, water supply of Amphur Muang Khonkhean is safe for using.
Keyword: Radium 266: Gamma spectrometry: water supply: Khonkaen