Sustainable access to clean water and basic sanitation is a crucial part of the Sustainable Development Goals (SDGs). Most sub-Saharan Africa countries are affected by wastewater pollution dilemma and poor effluent treatment systems. In Rwanda, the high population growth rate, urbanization, and industrialization has exacerbated wastewater generation beyond the bearing capacity of the available treatment systems. The wastewater discharge from diverse sectors during the last three decades become an important pollution source and is deteriorating the freshwater system (lakes, rivers, springs, groundwater, etc.), soil, fauna, and flora. Moreover, there is no centralized sewage system in Rwanda, only the existing decentralized wastewater treatment plants are inadequate to ensure basic sanitation. All these have placed the country on potential sewage catastrophe. Based on our knowledge, we know of no comparable study combining the wastewater pollution and the treatment systems failures in Sub-Saharan African countries. Consequently, this review highlights the wastewater pollution scenario and weaknesses of the treatment systems in Rwanda. Moreover, it proposes possible recommendations such as the improvement in operation and maintenance of treatment facilities, development of innovative and best affordable technology for Rwandan terrain, promoting public participation by improving joint efforts from different stakeholders to find their own way to protect water, and revolutionize wastewater quality standards by updating our own standard system for monitoring wastewater quality without compromising key health issues in Rwanda. Conclusively, this review will serve as all-inclusive model document on wastewater pollution and treatment systems statuses in developing countries, especially in Rwanda.