Background: Zanjan city with population of about 300,000 is supplied with groundwater resources for drinking water. Now, Zanjan sewage is disposed to cesspools. On the other hand, precipitation has decreased during the past decade. Because of the importance of the safe drinking water, this study was conducted to determine some chemicals and microbial characteristics in drinking water in 1999-2000.
Materials and Methods: This descriptive study was performed on total drinking water resources (wells) in Zanjan. During four seasons, 280 samples were collected and nitrate, nitrite and chloride concentrations were measureed by spectrophotometry and argantometric titration. Total coliforms and fecal coliforms were detected according to the approved methods. The data were analysed by Kroscal Wallis method.
Results: In this research, 36 drinking water wells were divided into two groups: 22 wells in the city and 14 wells out of the city. Mean concentrations of nitrate, nitrite and chloride in the wells inside the city, in comparison with the ones' outside, were statistically higher (p<0.0003, p<0.003, p<0.0003) respectively. In some wells inside the city, the nitrate was greater than of its standard limit, but the nitrite and chloride levels were less than the standard limits in all the wells. All the wells had desirable microbiological quality.
Conclusion: Nitrate and nitrite concentrations in some drinking water wells were undesirable and some of the wells were exposed to the contamination. Thus, it is necessary to determine the nitrate and nitrite concentrations in drinking water distribution system.
