DNWI: A Drinking Water Quality Index for Sustainable Urban Distribution Networks, Complemented by an Analysis of User Perception

This study evaluates drinking water quality in the urban distribution network of Loja, Ecuador, using the Distribution Network Water Quality Index (DNWI), complemented by citizen perception and expert-based weighting. Two sampling campaigns were conducted under low-rainfall conditions, collecting samples from household taps across three supply systems. Physicochemical and microbiological parameters were analyzed following standard methods, and normalized sub-indices were calculated to quantify deviations from regulatory thresholds. Additionally, a perception survey (n = 1015) and a Delphi-based expert evaluation were incorporated. Results revealed marked spatial variability, with critical DNWI values observed in distal sections of the CWS network (DNWI = 44.34), mainly driven by residual chlorine depletion and microbiological contamination. Non-parametric analysis (Kruskal–Wallis, p < 0.001) confirmed significant differences in perception across systems. Spearman correlations indicated that sensory water quality parameters, particularly color, strongly influence user satisfaction. The internal consistency of the perception scale was acceptable (Cronbach’s α = 0.634). The DNWI enables the identification of critical sectors, supports risk-based management, and provides an objective assessment of service management. Its comparison with citizen perception reveals gaps between sensory acceptability and technical quality, thereby strengthening sustainability, water governance, and progress toward SDG 6.