This study investigates the antibacterial efficacy of Moringa oleifera (M.oleifera) seeds as a natural coagulant for water purification, addressing the critical need for clean water due to its significant impact on human health and disease prevalence linked to contaminated water. The research was carried out to observe the effect of M. oleifera on the microbial load of Raw Water (RW) and treated water (TW) sourced from the Ibn Ziad wastewater treatment facility in Constantine. Results of bacteriological analyses show that the raw water is heavily polluted with high levels of the targeted bacteria: 4.4x10⁹ CFU/ml in total germs, 2.4x10⁴ CFU/100ml in total coliforms and total streptococci, and 1.1x10⁴ CFU/100ml in fecal coliforms, Escherichia coli, and fecal streptococci, with no decrease observed for sulfite-reducing clostridia. However, water treated with M. oleifera, at a dose of 20 g L⁻¹, demonstrates a significant reduction of 99% in total germs, 96% in total coliforms, and 98% in fecal coliforms, with a complete absence of Escherichia coli, streptococci, as well as a complete elimination of total sulfite-reducing clostridia , which falls with the standard guidelines for using this water in irrigation. The obtained results confirmed that M. oleifera seeds positively impact the reduction of pathogenic microorganisms found in wastewater.