Abstract: Groundwater is not only an important component of the hydrological cycle but also the most important source of water for drinking, domestic, industrial and agricultural uses. The present work is aimed at assessing the water quality index (WQI) for the groundwater of Doiwala block of Doon valley. This has been determined by collecting legacy data from concerned organization.For calculating the WQI, the following 11 parametershave been considered: pH, total hardness, calcium, magnesium, chloride, nitrate, sulphate, total dissolved solids, iron, manganese and fluorides.The WQI for these samples ranges from 30 to 330. The high value ofWQI has been found to be mainly from the higher values of iron, nitrate, totaldissolved solids, hardness, fluorides, bicarbonate and manganese in the groundwater. The results of analyses have been used to suggest models for predicting water quality.