Analysis of the microbial quality in drinking water distribution networks using the logistic regression model in Dasht-e Azadegan county, an arid region in the southwest of Iran

The microbial quality of water plays a key role in community health. The present study aimed to determine the microbial quality of the drinking water distribution networks in the urban and rural areas of Dasht-e Azadegan County, Iran and assess the influential factors in the quality of drinking water.In this descriptive-analytical study, 907 drinking water samples were collected from the urban and rural regions in Dasht-e Azadegan County in 2017. Turbidity, free residual chlorine, pH, total coliforms, and fecal coliforms were measured using the Standard Methods for the Examination of Water and Wastewater, and the results were analyzed using the logistic regression model. The free residual chlorine was within the range of 0-3 mg/L (mean: 0.72 mg/L). The free chlorine residual in 58% of the samples was within the recommended range of the World Health Organization (WHO) for drinking water, and 29% of the samples had higher turbidity than the accepted limit of the WHO (5NTU). In addition, 7.7% and 16% of the samples were infected with fecal and total coliforms, respectively. According to the results of the logistic regression analysis, coliform contamination was most significantly associated with free chlorine residual and turbidity, and reduced free chlorine residual was most effective in coliform contamination.