Evaluation of chemical quality of drinking water in Divandareh villages with emphasis on nitrate concentration

Nowadays, the increasing concentration of pollutants in water resources, especially ground water, has been a matter of concern. Nitrate has been considered as a chemical indicator of water pollution for a long time. The aim of this study was to determine the chemical characteristics of drinking water and changes of nitrate in drinking water in Diwandareh villages. This was a cross-sectional study to determine the quality of drinking water of 30 villages in Divandareh. A total of 60 samples were obtained in two phases from water supplies and were analyzed according to the standard methods. Descriptive statistics, Piper, Schuler and Wilcox diagrams were used to interpret the results. The results showed that apart from nitrate, the concentrations of the other chemical quality parameters were below the standard limits. The mean and standard deviation of nitrate during the first and second stages of sampling in water sources were 26.13 ± 25.61 mg L-1 and 28.47 ± 29.80 mg L-1, respectively. According to Schuler diagram, the drinking water quality was moderate to good. Although the mean nitrate concentration in 80% of samples was lower than the latest national standard for nitrate, continuation of the current trend, particularly in the agricultural activities and uncontrolled use of groundwater resources in agriculture will change and lower the quality of water. Therefore, monitoring of agricultural practices and fertilizer use are necessary.