The Millennium Development Goals aim to achieve the sustainable development and to contribute improving access to water supply, sanitation, and energy, and to reduce hunger in the world. Energy and water are essential resources for food production, however, are becoming scarce. In this context an integration of the complete water management cycle includes water conservation and reclamation, storage of reclaimed water and rainwater, and wastewater treatment mainly in decentralized models. Wastewater treatment systems can generate products such as: renewable energy, fertilizers and water. This study focuses on the relations between wastewater treatment systems and its environmental impacts, besides to indicate potential solutions. In addition, it is also presented results from an experimental greywater treatment system operated at the university. The objective of this study was to address some Brazilian experiences of centralized wastewater treatment plant (large scale) and decentralized wastewater treatment plant (small scale). We expect that the results of this study can offer a review of strategies of wastewater treatment to implement in urban areas in Brazil, and to create subsidies for the planning of new wastewater treatment plants with low environmental impacts, including sustainable solutions (e.g., water reuse).