Delta regions face significant wastewater management challenges due to rapid urbanization, industrial expansion, and climate change impacts. Inadequate wastewater treatment, poor sanitation infrastructure, and the direct discharge of pollutants into water bodies contribute to severe environmental degradation, including water eutrophication and biodiversity loss. Despite the growing urgency, there remains a critical gap in the development of integrated, climate-sensitive, and context-specific wastewater management strategies for delta environments. To address these challenges, innovative technologies such as decentralized wastewater treatment, multi-level reuse systems, and nature-based solutions are being explored to enhance efficiency and sustainability. Findings suggest that effective wastewater management in delta regions requires more than just infrastructure development—emphasizing adaptive governance, ecological protection, and inclusive community participation. Case studies from the Niger Delta, Yangtze River Delta, Mekong Delta, and others highlight both shared and site-specific issues, reinforcing the importance of localized, context-driven solutions. Policy instruments, such as integrated water resource management, regulatory enforcement, and community engagement, play a crucial role in mitigating wastewater-related risks. This chapter examines key wastewater challenges in delta regions worldwide, highlights the need for holistic, multi-scalar responses, and the underscores the technological advancements and governance innovations essential for achieving sustainable water management.