The increasing complexity of water and wastewater treatment necessitates the adoption of advanced digital solutions for efficient, sustainable, and secure operations. This chapter explores the integration of Digital Twins (DTs) with emerging technologies such as IoT, AI, Big Data, blockchain, cloud computing, and edge computing to enhance the performance of water management infrastructures. Beginning with an overview of the challenges in wastewater treatment, the chapter introduces the concept and evolution of DTs, emphasizing their growing role in environmental engineering. The discussion then focuses on the applicability of DTs in both water supply and wastewater treatment systems, including real-time monitoring, predictive maintenance, and process optimization. Furthermore, the chapter highlights how blockchain ensures data integrity and transparency, while cloud and edge computing enable scalable, low-latency data processing for DT operations. Real-world case studies of DT-driven drinking water systems are presented to illustrate the practical implementation and operational benefits. Overall, the chapter positions DTs as a transformative framework for intelligent water management, enabling proactive decision-making, enhanced resilience, and long-term sustainability.