Fecal contamination is one of the main freshwater quality problems worldwide. One of the proposed solutions for this problem is the treatment of the effluents at domestic orlocal level with microbial consortia such as effective microorganisms from native origin (MEN in Spanish). In this work we evaluated the ability of a MEN formulation produced in Uruguay to reduce fecal contamination in domestic effluents. To achieve this, experimentswere carried out at different scales, from in vitro to domestic septic tanks and in a section of the Malvín stream (in situ), combining liquid with solid MEN formulation and using fecal coliforms (FC) and particulate organic matter as performance indicators. Both at the laboratory level and in the septic tanks, CF decreased significantly after 8 weeks ofapplication. In the Malvín stream, a decrease in CF and a visual recovery of the water course were observed, with increased transparency and dissolved oxygen concentration. The results from this work suggest that MEN application to domestic wastewater represents a promising approach to reduce fecal contamination of freshwater andemphasize the need to change the manufacturing habits and management of septic tanks.