Securing sustainable access to water resources is a critical concern for all nations bordering the Mediterranean Sea, and Algeria is no exception. Leveraging its extensive 1,200-kilometer coastline, Algeria has embraced desalination as a key strategy, treating both seawater and brackish water sources. This approach provides potable water to inland towns and cities, extending as far as 60 kilometers from the coast. Currently, Algeria boasts an impressive network of 21 desalination plants, with a combined daily production capacity of 2.6 million cubic meters. The majority of these facilities utilize reverse osmosis, a widely employed desalination technology. This study focused on the Bousfer mini-desalination plant situated on Algeria's western coast. Various water samples were analyzed throughout the desalination process: seawater intake, post-desalination (osmosis) water, remineralized drinking water, and the resulting brine wastewater. A physicochemical and bacteriological analysis was conducted to assess water quality at each stage. Statistical comparisons were performed using paired-sample T-tests for seawater and osmosis water, and one-sample T-tests were used to compare drinking water and wastewater against established international standards. The analysis revealed significant reductions (p-value < 0.001) in most physicochemical parameters for the reverse osmosis water, including conductivity, total dissolved solids (TDS), alkalinity, total hardness, chlorides, calcium, and magnesium. Conversely, these parameters were significantly elevated in the brine wastewater. The bacteriological analysis confirmed the absence of harmful bacteria like E. coli, enterococci, and sulphite-reducing clostridia in the final drinking water. However, this study also highlighted a negative environmental externality, the presence of debris and foam layers on the water surface near the desalination plant outlet, attributed to chemical discharges, which poses a potential nuisance for tourists visiting nearby Bousfer beaches.