The study was conducted on domestic wastewater collected at the National Sanitation Office monitoring station and treated using three experimental cylindrical filters (200 L) with a filtering medium 0.70 m high. The treatment achieved average removal efficiencies of 41.42% for biochemical oxygen demand (BOD₅), 39.11% for chemical oxygen demand (COD), and 23.30% for total suspended solids (TSS), all within acceptable ranges. Average removal rates of 40.50% and 57.64% were obtained for nitrogen and orthophosphate, respectively, along with a significant improvement in hydrogen potential (pH). The links between correlated variables were investigated using multivariate statistical methods, including principal component analysis and hierarchical clustering. The results show a significant reduction in pollutant loads after treatment, particularly in BOD₅, COD, TSS, nitrogen, orthophosphate, and hydrogen potential. PCA highlights the principal axes of variability, and hierarchical classification distinguishes groups of parameters with similar water quality.