Microbial Contamination in Drinking Water Sources: A Study on Safety and Public Health

This study evaluated temporal trends in microbiological water quality in Ceará and Paraíba, Northeastern Brazil, from 2014 to 2025, using SISAGUA/DATASUS data. Escherichia coli was used as an indicator of fecal contamination. Four supply modalities were assessed: Water Supply Systems (SAA), Collective Alternative Supply (SAC), Individual Alternative Supply (SAI), and tanker-truck supply. Statistical analysis included ANOVA, Tukey’s test (α ≤ 0.05), and correlation matrices with precipitation and temperature. A total of 716,961 samples were analyzed (541,308 in Ceará; 175,653 in Paraíba). Ceará showed higher compliance with drinking water standards (69.5%) than Paraíba (57.3%). SAA systems presented the best microbiological performance, while SAC, SAI, and tanker-truck systems showed higher non-compliance and inconclusive results, especially in rural areas. Correlation analysis indicated stronger climatic effects in Ceará, where precipitation was positively associated with compliant SAC and SAI results (r = 0.96). In Paraíba, precipitation showed a strong negative correlation with tanker-truck analysis (r = −0.93) and compliant results (r = −1.00), indicating lower demand in wet years. Temperature generally showed negative correlations with operational indicators. According to this study, Centralized systems were more efficient and resilient than alternative or emergency solutions.