Microbiological Water Quality and Structural Determinants in Preschools of Matehuala, Mexico: Implications for Sustainability and Equity in Safe Water Access

Access to microbiologically safe water in preschool educational settings constitutes a pressing public health challenge, particularly in rural areas with deficient infrastructure. Repeated exposure to enteropathogens present in contaminated water has been associated with acute gastrointestinal infections, environmental enteropathy, and disruptions in the intestinal microbiota of young children. Motivated by this concern, the present study evaluates the microbiological quality of water in 32 public preschool facilities in the municipality of Matehuala, San Luis Potosí—18 urban and 14 rural—by analyzing the presence of aerobic mesophilic bacteria (AMB), total coliforms (TC), fecal coliforms (FC), and helminth eggs. The assessment was conducted in accordance with Mexican standards NOM-092-SSA1-1994 and NOM-230-SSA1-2002 and supplemented with the World Health Organization’s guidelines for drinking-water quality. The findings revealed a marked territorial disparity: 100% of rural schools that relied on rooftop water tanks exceeded permissible limits for TC, and 35.7% tested positive for FC. In contrast, all urban schools—supplied through piped water systems—complied with current regulations. Statistical analysis (Mann–Whitney U test, p < 0.05) confirmed significant differences in microbiological contamination based on geographic location and type of water supply. In all FC-positive cases, a lack of sewage infrastructure and inadequate sanitation practices in storage containers were documented. These results demonstrate that formal access to water does not ensure its microbiological safety, particularly in settings with poor structural conditions. The study underscores the urgent need to implement point-of-use water treatment technologies, establish regular microbiological monitoring protocols, and provide training for educational staff in water hygiene practices.