ABSTRACT Aqueous plant extracts have been proven to be effective in reducing microorganisms due to their high concentration of bioactive compounds such as polyphenols and carotenoids which have antimicrobial and antioxidant activity. Plant extracts are indeed concentrated preparations with something like a liquid, solid, or viscous consistency. The present study was focused on the antimicrobial effect of the aqueous extract of mint leaves (Mentha longifolia) and the aqueous extract of basil leaves (Ocimum basilicum) on bacterial strains (Escherichia coli, Enterococcus sp., Bacillus sp. and Staphylococcus sp.) and fungal strain (Aspergillus niger, Candida albicans and Penicillium digitatum). Results show that aqueous extract of mint leaves is more effective than the aqueous extract of basil leaves. Aqueous extract of mint leaves was used with different doses and at different contact time to reduce total coliform and fecal coliform from raw river water.