Tehran University of Medical Sciences Iranian Journal of Public Health 2251-6085 21 1-4 1992 06 15 1 10 F.Vaezi A. Mesdaghinia 2015 10 03 Natural sources of water contain some halogenated organic compounds after disinfection by chlorine. Trihalomethanes are one group of the chlorination by products that suspected of being carcinogenic inhuman unfortunately, these compounds are in finished water of all treatment plants that use chlorine as a disinfectant. In this study, the concentration of total THMS of water treated in the water treatment plant No.1 of Tehran had been measured by spectrophotometric method, along the month of June, 1371. Results of experiments have shown that organic contents of Tehran drinking water were not considerable in the period of survey. The mean concentration of TTHMS in water samples is estimated to be 28 micrograms per liter and none of the analyzed samples was considered polluted. https://ijph.tums.ac.ir/index.php/ijph/article/view/1596 https://ijph.tums.ac.ir/index.php/ijph/article/download/1596/1577