Water quality inequalities in Brazilian municipalities: surveillance challenges for the 21st century

Abstract

Surveillance is the main strategy to ensure water quality. This study aimed to analyze the basic water quality parameters in Brazilian municipalities in 2018 according to their demographic, socioeconomic and geographic characteristics in order to explore the challenges of surveillance for the 21st century. We conducted a cross-sectional ecological study using official data from the Information System for Water Quality Surveillance for Human Consumption. More than 420K records from water supply systems across all 5,570 municipalities were submitted to a data cleaning and validation protocol processed with RStudio software. Variables included turbidity, free residual chlorine, pH, fluoride concentration, and the absence of Escherichia coli. Municipalities were categorized by population size, Human Development Index, and macro-region. The percentage of municipalities with valid information and compliance with expected standards was calculated based on institutional and scientific criteria. The results showed that E. coli and turbidity yielded the best performance (more than 75% of the municipalities had valid information) while pH and fluoride, the worst (less than 50% of the municipalities). In relation to the conformity, among municipalities with validated information, 80% or more were compliant with expected patterns for turbidity, free residual chlorine and pH and about half for E. coli and fluoride. In conclusion, the water quality surveillance was well implemented in one at each five Brazilian municipalities with significant differences according to demographic, socioeconomic and geographic characteristics of the municipalities.