Survey the Nitrate Concentration in Drinking Water Distribution Systems of Kashan County, Iran

High concentration of nitrate is a prevalent problem in water resources. Untreated wastewater due to municipal, industrial and agricultural activities is the main potential source of nitrate contamination of groundwater and surface water. The maximum permissible level of nitrate concentration has been established to be 45 mg/L by WHO and US–EPA. Health problems, such as Methemoglobinemia in babies, can occur in the case of exposure with levels more than 45 mg/L. Nitrate concentration was measured in drinking water distribution systems of Kashan and its six surrounding towns in 2013. Samples were taken under standard conditions. 25 sampling points were selected based on the population density and the size of water distribution systems. Nitrate concentration was measured using spectrophotometry. Finally, the data analysis was carried out with SPSS software. The average concentration of nitrate was 17.5 mg/L. Maximum and minimum levels of nitrate in drinking water sources were 27.4 mg/L and 9.5 mg/L, respectively. Also, there were significant differences between the average concentrations of nitrate among sampling points in Kashan and the six neighboring towns (p<0.05). The nitrate concentrations in 68% of total samples were below 20 mg/L (i.e. slightly contaminated), 32% were between 20 – 45 mg/L (i.e. contaminated), and nitrate concentrations more than 45 mg/L (i.e. highly contaminated) were not reported. The average nitrate concentration in all sampling points meets WHO guidelines. It can be concluded that nitrate contamination of the water distribution networks in Kashan and other towns neighboring it had the appropriate conditions. But comparing the findings of the present study with those performed in Kashan one decade ago (2006) it can be concluded that the average concentration of nitrate in drinking water sources is increased continuously.