The present work is aimed to calculate the water quality index (WQI) for irrigation suitability and livestock drinking purposes of the groundwater of Aligarh. WQI is calculated on the basis of Weighted Arithmetic Index by analysing 13 physico-chemical parameters. The parameters namely pH, total alkalinity, total hardness,
 &  hardness, turbidity, conductivity, total dissolved solids (TDS), total solid (TS), total suspended solid (TSS), dissolved oxygen (DO), chemical oxygen demand (COD) and chloride. The WQI for these samples range from 37.10-93.93. The analysis reveals that the groundwater of the area needs some treatment before consumption, and it is need to be protected from the perils of contamination.