The environmental, economic, and social dimensions of sustainability, were connected in a systems ecology model with focus on wastewater treatment. Life Cycle Assessment and similar approaches are the most common systems analysis models in the wastewater treatment context. These models are beneficial, but are not the only possible approach to systems analysis. The model in this paper showed that the social and economic dimensions were inseparable intertwined, and both of them dependent on the environmental dimension for ecosystem services in the form of natural resources and regenerating capacity. The holistic view, as applied by a systems ecology approach, put focus on how sustainable wastewater treatment are limited to deliver something that can be assimilated by the environmental systems, and in the best applications, produce something that is again useful to the society.