This study investigates the complex interactions between operational and financial variables that influence infrastructure investment in Romania’s wastewater sector, a serious area for environmental sustainability and compliance with European environmental standards. Using a comprehensive dataset covering all regional water service operators, accounting for over 90% of the country’s population, across the period 2012–2022, the analysis employs dynamic panel data methods to examine how treated wastewater volumes, operating expenditures, revenues, tariffs and the number of connected users shape investment decisions and the modernization of wastewater infrastructure. The results reveal strong links between operational performance and investment behavior, indicating that revenues from wastewater services and efficiency in organic pollutant removal (CBO5) are key determinants of capital investment. The findings further show that an expanding user base generates substantial investment needs, supporting the extension and upgrading of wastewater treatment networks. By combining a dynamic econometric framework with a comprehensive national sample, the study makes an original contribution to the literature by providing robust empirical evidence on the interaction between financial performance, operational efficiency and sustainability objectives in the wastewater sector. The results underscore the importance of good financial planning, strategic management and sustainable investment policies, and offer relevant insights for policymakers, utility operators and researchers concerned with improving wastewater infrastructure performance under current economic and environmental challenges.

This paper analyses the determinants of the economic and operational sustainability of sewerage services at the level of an economic operator, using data from an 11-year period, focusing on investments from European funds, network extension, environmental compliance and tariff policy. The results reveal uneven distribution of investments and high volumes of untreated wastewater, which reveal deficiencies in planning and infrastructure. Connected population is identified as a key factor for financial sustainability. Slow network expansion and tariff stability limit the ability of operators to invest in modernization. The results provide practical directions for improving the management of sewerage services in the long term.

Sustainable water resources management is a major challenge in the context of climate change, population growth and socio-economic pressures on hydrological systems. This study conducts a bibliometric analysis of the literature dedicated to sustainable water management for the period 1997–2024, with the objective of identifying the geographical distribution of scientific production, thematic evolution and the internal structure of the field. Methodologically, the research uses keyword frequency analysis, thematic trend assessment and bibliographic coupling, with the application of the Louvain algorithm for cluster detection. The results highlight a significant concentration of research in developed and emerging economies, such as China, the United States and Germany, as well as a conceptual maturation marked by the integration of climate change, water security and IWRM approaches. The study confirms the interdisciplinary nature and applicative orientation of the field, highlighting emerging research directions and their relevance for public policies and sustainable planning.

This study analyses the relationships between investments, network expansion, operational costs, tariffs and environmental compliance in sewage services in Romania, over the period 2012–2022. Using a quantitative methodology based on correlation matrix and principal component analysis (PCA), the research highlights the interdependencies between key indicators. The results show that connected population and tariffs are determinants of economic sustainability, while investments indirectly contribute to improving environmental compliance. The study highlights the need for an integrated strategy that combines financial efficiency, infrastructure modernization and environmental compliance to ensure long-term sustainability.