To assess the environmental impact of wastewater treatment, life cycle assessment (LCA) is a frequently applied instrument. However, these studies often require large amounts of data. The complexity and heterogeneity of these data result in the need for a systematic data management approach. Especially the generation of the life cycle inventory (LCI) holds the potential to be facilitated by automation. A case study in the wastewater sector was used to demonstrate the implementation of data management. A database structure was developed to store the raw data of the wastewater plants (WWTPs) and make it accessible through code. The code interacted with the database, implemented calculations, and automatically created the inventory based on the processed data. The database provides a consistent structure for the raw data and can also be used for backup purposes. Because it is machine-readable it can be accessed through the code that enables the automated generation of the LCI. As a proof of concept, a sequence of the code is provided with a user interface and can be tested online. We found that for most use cases, basic programming tools were sufficient for systematic data management, and, therefore, the approach is considered accessible for LCA practitioners.