Insufficient Chlorination as the Critical Determinant of Microbiological Non-Compliance in Rural Water Systems: First Integrated Assessment in Azuero, Panama

Abstract

Access to safe drinking water in rural communities depends heavily on day-to-day system operation and sustained disinfection, both of which are often fragile. Although global reports describe widespread microbiological contamination of rural water supplies, there remains a lack of integrated studies that pinpoint the specific drivers of failure in regions such as Azuero, Panama. In this cross-sectional study, we evaluated rural water systems in the municipalities of Chitré, La Villa de Los Santos, and Santa Ana, using a combination of microbiological and physicochemical indicators. Total coliforms, Escherichia coli, and nematodes were assessed by membrane filtration and microscopic examination, while pH and free residual chlorine were measured in situ. Nematodes were not detected in any sample. In contrast, total coliforms were detected at all sampling points, with concentrations ranging from 1 to 4,556 CFU/100 mL, clearly above the regulatory limit (<1 CFU/100 mL). E. coli was found at three sites (47–110 CFU/100 mL). Although pH values complied with national standards, free residual chlorine was frequently absent or below the recommended range. No significant differences in bacterial loads were observed between tanks and wells (p > 0.05), but a weak negative correlation between residual chlorine and total coliforms (r = –0.25) suggests that inconsistent chlorination is the main factor associated with microbiological non-compliance. This work provides the first integrated assessment of rural water systems in the Azuero region, jointly analysing microbiological, physicochemical, and operational information. The results show that inadequate chlorination—rather than infrastructure type—undermines water quality, and they point to an urgent need to reinforce community-level disinfection practices, preventive maintenance, and continuous monitoring in rural Panama.