Application of DWQI for comprehensive evaluation of drinking water quality

Document Type : Research Article


1 MSc Student, Department of Geology, Urmia University, Urmia, Iran

2 Assistant Professor, Department of Soil Science, Urmia University, Urmia, Iran

3 Associate Professor, Department of Geology, Urmia University, Urmia, Iran


Water quality is considered as one of the most important factors in development of the civilizations and sustainability of human activities. Water quality can be evaluated by comparing each of the chemical properties in water samples with their reference values. The single parameter comparison method is characterized by some limitations and a comprehensive evaluation of  water quality is not possible using this method. Thus, water quality indices have been developed during the last 3 decades. The aim of this study was to comprehensively evaluate the water quality in Ardabil aquifer with a newly proposed drinking water quality index (DWQIProposed). The DWQIProposed  was also compared with the conventional water quality indices including DWQIA and DWQIG. Water samples were collected from 60 wells in Ardabil aquifer during the September 2014 and analyzed for 21 different physical, chemical, and biological properties. DWQIProposed were computed in four steps including parameter selection, parameter categorization, development of sub-index with regression statistics, and aggregation of the sub indices. Based on the obtained results, although there was a quantitative difference between the DWQIProposed and DWQIG, their probability distribution functions reflect a similar pattern. DWQIProposed and DWQIA have similar values for samples with excellent water quality. ANOVA results indicated that the mean difference between three indices is significant (P<0.05) but there was a high correlation between these three indices (r=0.98-0.99, P<0.001). Among the health related properties, Nitrate has the highest correlation coefficient with water quality indices (r=0.712-0.815, P<0.001) which emphasizes the effect of nitrate on water quality at the region. Water quality indices are considered to have strong spatial dependence and their kriging maps clearly showed the declining trend in water quality when moved from north-eastern parts of the region to the south-western parts.


Main Subjects

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Volume 4, Issue 2
June 2017
Pages 421-436
  • Receive Date: 18 December 2016
  • Revise Date: 19 January 2017
  • Accept Date: 19 January 2017
  • First Publish Date: 22 June 2017