Socioeconomic inequality and access to urban water and sanitation services in Brazil’s Southeast Region: a spatial analysis from a human–water systems perspective

Access to water supply and sanitation services is widely recognized as a fundamental human right and a central component of human–water systems. In countries marked by persistent socioeconomic inequality, however, the provision of these services remains unevenly distributed across space, reflecting long-standing territorial and institutional disparities. Brazil represents a critical case in this regard, combining ambitious universalization targets with significant differences in access to water and sanitation infrastructure across municipalities.

This study investigates the spatial relationship between average household income and access to urban water supply and sanitation services in Brazil’s Southeast Region. The regional focus is justified by the higher completeness and consistency of sanitation data available for the year 2020, which allows for a more robust spatial analysis. Municipal-level income data from the Fundação Getulio Vargas (FGV) were combined with urban service coverage indicators from the National Sanitation Information System (SINISA), specifically the urban water supply coverage index (IN023) and the urban sewerage coverage index (IN047). The analysis was conducted in a GIS environment (ArcGIS Pro). Spatial dependence was first assessed using Global Moran’s I statistics, followed by Local Indicators of Spatial Association (LISA) to identify clusters and spatial outliers. To further explore the interaction between socioeconomic conditions and service provision, income and sanitation LISA results were overlaid, enabling the identification of municipalities where low income and limited access to services coexist spatially.

The results indicate statistically significant positive spatial autocorrelation for income, water supply coverage, and sewerage coverage, suggesting that municipalities with similar socioeconomic and infrastructure characteristics tend to cluster geographically. The combined cluster analysis highlights territorially structured inequalities, including areas characterized by the simultaneous presence of low income and deficient access to water and sanitation services, as well as spatial mismatches where service coverage and income levels diverge. These patterns indicate that disparities in access are not randomly distributed, but instead reflect broader socio-spatial dynamics shaping human–water interactions in the region.

By adopting a human–water systems perspective, this study emphasizes that access to water and sanitation services is closely linked to territorial and socioeconomic conditions. The findings reinforce the importance of incorporating spatial and socioeconomic criteria into water and sanitation planning and demonstrate how spatial statistical approaches can support more equitable and evidence-based public policy design.