A combination of the surfactant SDS with levulinic acid produces a synergistic effect in relation to the antimicrobial effectiveness of the individual compounds, allowing the formulation of compositions wherein the active agents are present at concentrations effective to reduce bacterial and fungal counts in liquids, including, but not limited to, water and other beverages, without altering the organoleptic properties of the treated food substance. The active agents are FDA-approved as food additives, and the treated beverages can be any aqueous-based beverage consumable by humans or animals. The levulinic acid-SDS combination is also suitable for reducing or eliminating the microbial population on the surfaces of water and beverage containers, and the machinery and facilities for the bottling of liquids.