Global water quality indices: Development, implications, and limitations

Abstract

Water quality index is crucial for improving water quality and clean water supply to achieve sustainable development goals directly related to water, agriculture, biodiversity, health, and climate actions. Water quality index examines the vital relationship between water supply and demand, focusing on the critical role that water quality (WQ) plays in sustainable development and integrated environmental management. This study evaluates the methodology and limitations of several studies by doing a thorough examination of regional and global WQ indices and synthesizing the results. Water Quality Indices (WQIs) have been used to measure WQ since the 1960s, offering a mechanism for changes in WQ at specific needs and environmental challenges. This review study assesses overall water quality using global and regional WQ indexes based on several studies and aims to provide a detailed analysis of various WQIs utilized across the globe. The WQIs stated WQ measurements into a single number, which are categorized as poor, marginal, fair, excellent, and exceptional, to depict changes clearly and understandably in WQ. However, region-specific WQIs are required due to the variety of standards established by national and international organizations, as well as different pollution prevention elements. Thus, there is continual interest in developing exact WQIs suitable for a region or geographic area. Still, structured and in-depth literature analysis is required to examine current WQIs to research, evaluate, and highlight the drawbacks of various methodologies employed in each development phase. This review offers insightful information for researchers, decision-makers, and practitioners tackling the ever-changing problems of water quality in the interest of sustainable water resource management. The debate concentrates on various WQI-related topics, such as how multiple WQIs have evolved, what variables define their parameter requirements, what restrictions WQIs have, how widely WQIs are used, and what benefits WQIs have over one another regarding worldwide applicability.