Abstarct: In recent decades, with increasing population growth and development of industrial and agricultural activities, Groundwater and surface water contamination has increased dramatically.Some of these pollutants are organic compounds from natural and artificial sources which enter to surface water and groundwater.The presence of these compounds in drinking water during chlorination produces substances that damage to human health. This study aimed to assess the Total Organic Carbon (TOC), in drinking water resources of Shahrood city. Study area includes part of the mountain Tepal that is located in the west of the Shahrood city. To evaluate the values of Total Organic Carbon (TOC), water samples from 9 drinking walls of Shahrood city were collected in May and October 2016. For all samples, electrical conductivity and pH values were measured in situ. Measurements show that the electrical conductivity values ranges from 301 to 614 µmhos/cm in May and from 209 to 592 µmhos /cm in October. PH values ranges from 7.75 to 7.90 in May and from 7.44 to 7.81 in October. The values electrical conductivity and pH for all samples is within the allowable range of drinking water. The concentration of Total Organic Carbon (TOC) was measured by TOC meter model Multi N/C 3100 at Water and Environment Laboratory in Shahrood University of Hydrology. The values of Total Organic Carbon compared to the standard USEPA show that the concentration of Total Organic Carbon in at samples are above the limit value specified in the USEPA standard. The Total Organic Carbon content declined in samples related to October compared to May. High concentrations of total organic carbon in water samples in the study area presumably is related to the existence of coal deposits in shales and marls of Shemshak formation. In addition, the low concentration of Total Organic Carbon in the October relative to May, related to the effects dillution recharged water to the karst aquifer and water aquifer. Lower values of electrical conductivity in October confirms the above subject.