Development of an Overall Water Quality Index (OWQI) for Surface Water in Indian Context

A number of water quality indices based on classification criteria, sub-indices and aggregation function have been developed by the researchers for categorizing the water quality for different uses. In the present study, a general Overall Water Quality Index (OWQI) is developed to classify the surface water into five categories, viz. excellent, good, fair, poor and polluted. For this purpose, the concentration ranges have been defined on the basis of the Indian Standards (IS) and Central Pollution Control Board (CPCB) standards also taking into account other International standards of World Health Organization (WHO) and European Commission (EC). Sixteen parameters are selected based on social and environmental impact and weights are assigned on their relative importance to impact the quality of water. The proposed index improves understanding of water quality issues by integrating complex data and generates a score which describes the status of water quality. The proposed index will be very useful for the water management authorities to maintain good health of surface water resources.