Assessment of Supply Water Quality Using GIS Tool for Selected Locations in Delhi—A Case Study

The importance of water quality is well understood, and it becomes even more critical when is use for drinking purposes. A case study was carried out to know the applicability of GIS tool for determining the quality of supply water. Water samples from 21 houses at different locations of Delhi were collected. Sample analysis was done for physicochemical parameters viz., pH, EC, TDS, Total Hardness, Total Alkalinity, Chloride, Fluoride, and Nitrate. The water quality data from these selected locations was analyzed using Geographical Information System (GIS) Technique. GIS software did interpolation through the inverse distance weighted (IDW) method to know the water quality (WQ) in different part of the city for various parameters mentioned above and prepare thematic maps from the analysis of water quality data as a database. These thematic maps show the distribution of different water quality parameters. Using Weighted Arithmetic Index (WAI) method, Water Quality Index is calculated. After that, the Drinking Water Quality Index (DWQI) map was generated using thematic layer, reclassification, and weight value assigned in weighted overlay tools in GIS software. Five categories viz., excellent, good, satisfactory, poor, and very poor is assign to describe DWQI. Out of all the selected locations, DWQI was good only at two locations, whereas, at the remaining sites, the DWQI was found satisfactory. However, the overall water quality was found suitable for human consumption. The analysis outcome was represented as maps that will be advantageous to know the water quality status for the area under study. The spatial database established can be a reliable technique for monitoring and managing water quality in the water supply system.