Application of N fertilizers in agricultural operations is one of the important sources of nitrate entry into groundwater. In Iran, especially in coastal areas with a high groundwater level, in agricultural areas, there is a risk of pollution of groundwater and surface water to nitrates. This research was conducted with the aim of determining the concentration of chemical parameters of drinking water wells in a Tonekabon village and comparing with acceptable standards. The present study was carried out on groundwater resources of Zawar village of Tonekabon city for six months and then data were analyzed to determine the concentration of chemical parameters and water resources type based on anions and cations in water. The results of this study during the investigation of different wells showed that the total number of samples tested from a drinking water well in Zawar, Tonekabon, the range of nitrate concentration from 8 to 33.7 mg / L, TDS from 233 to 435 mg in liters and the total hardness varied from 211 to 372 mg/L. According to the definition of pollution, the wells were classified in the permitted class in terms of nitrate. However, the approach of nitrate levels in some wells to 20 mg per liter (a sign of the impact of human activities) is also worthy of serious consideration. determining the quality of the area reduces the amount of nitrate in the groundwater and thus increases the quality of groundwater.