Selecting reliable suppliers is crucial for supply chain management in construction, as it directly influences project quality. In multi-family buildings, selecting unreliable suppliers for sanitary facility materials negatively impacts quality, with 60% of incidents attributed to substandard materials. This study proposes implementing the Choosing by Advantages (CBA) methodology to improve supplier reliability. CBA provides a standardized process that allows objectively comparing the advantages of each option, ensuring transparent and safe decisions. It was implemented in Excel format, making it easy to use and accessible to professionals. The research included surveys and interviews with engineers from three multi-family projects in Lima, to identify and analyze the traditional process. From this information, a new approach based on the CBA methodology was developed, which was simulated in a project to evaluate its effectiveness. The results show that the CBA process increases reliability in the selection of sanitary materials suppliers, going from 65% to 95%, as validated by surveys with engineers, confirming the effectiveness of the new approach. In conclusion, CBA is an effective methodology that not only improves supplier reliability but also ensures higher-quality materials in multifamily construction projects, which is crucial for the overall success of the project.