Determination of Trihalomethanes Concentrations in the Drinking Water Distribution Network of Isfahan City, Iran, during the Years 2015-2016

The goal of this study was to determine the concentration of trihalomethanes compounds in drinking water distribution network of Isfahan City, Iran, as well as comparison of data with previously reported values. This descriptive cross-sectional study was performed during the years 2015-2016. The samples were taken at sampling periods (totally 12 periods) from eighteen sampling points in one working day, based on standard methods. Trihalomethanes were determined based on ISO-10301:1997 and ISRI 16469 standards using gas chromatography-mass spectrometric (GC-MS) method. Other parameters including temperature, pH, and residual chlorine were measured at sampling sites. Findings: Among the measured concentration of four trihahomethane species, only chloroform showed measurable values. The average concentration of chloroform in Isfahan water distribution network was 19.8, 16.2, 19.7, and 12.9 mg/l in spring, summer, autumn, and winter, respectively. The average concentration of residual free chlorine was 0.6, 0.6, 0.5, and 0.6 mg/l in same seasons, respectively. The current study reveals that the average concentration of chloroform measured in summer is approximately 20% higher than those reported values at 2013. The appeared trend in concentration of chloroform shows the importance of continuous monitoring of these compounds, and the implementation of their reduction strategies for the coming years. By the way, the quality of Isfahan drinking water respect to the mentioned species and residual chlorine currently passes credible standards as well as the United States Environmental Protection Agency (US-EPA).