Evaluation of Drinking Water Quality from Multiple Sources in Relation to WHO Standards in Prasat Bakong District, Siem Reap Province

Access to safe drinking water remains a major public health concern in rural Cambodia. This study evaluated the physicochemical and microbiological quality of four water sources—rainwater, pond biosand-treated, well biosand-treated, and city-supplied water—in Prasat Bakong District, Siem Reap Province, and compared them with World Health Organization (WHO) standards. Parameters analyzed included pH, turbidity, electrical conductivity (EC), total dissolved solids (TDS), manganese (Mn), iron (Fe), nitrate (NO₃⁻), phosphate (PO₄³⁻), total hardness, arsenic (As), Escherichia coli (E. coli), and total coliforms. Most physicochemical parameters complied with WHO guidelines, with pH ranging from 6.6 to 7.6 and TDS below 500 ppm. However, turbidity, arsenic, and microbial contamination exceeded acceptable limits in some sources. Pond biosand-treated water showed the highest turbidity (14.7 NTU), elevated Fe (0.19 mg/L), and as (0.043 mg/L). Rainwater contained high microbial loads (E. coli: 67 CFU/100 mL; total coliforms: 175 CFU/100 mL), while well biosand-treated water met most standards except for As, which reached the WHO limit (0.01 mg/L). City-supplied water consistently met all safety criteria. Correlation analysis revealed strong associations between turbidity, Fe, and As, and between phosphate and microbial indicators, suggesting shared contamination pathways. Principal Component Analysis (PCA) explained 78% of total variance, distinguishing contamination profiles: pond water with turbidity and metals, rainwater with microbial contamination, well water with mineralization and arsenic, and city water with minimal pollutants. Overall, only city water was consistently safe for consumption, emphasizing the need for regular monitoring and maintenance of biosand systems to ensure safe water access in rural Cambodia.