Water quality monitoring is increasingly critical for environmental and public health, yet traditional methods often suffer from limitations such as high costs, labor intensity, and delayed responsiveness. This chapter explores the transformative impact of emerging technologies on water quality assessment, highlighting how innovations like smart sensors, biosensors, Internet of Things (IoT), remote sensing, artificial intelligence (AI), machine learning (ML), microfluidics, and blockchain are revolutionizing the field. These technologies enable real-time, cost-effective, and scalable solutions that overcome the spatial and temporal limitations of conventional monitoring techniques. Smart sensors and biosensors offer continuous monitoring of key water parameters, while IoT and wireless sensor networks (WSNs) allow for remote and automated data collection. AI and ML enhance predictive analytics and early warning systems, and satellite technologies provide spatially extensive insights into aquatic ecosystems. Microfluidic and nanotechnology platforms enable rapid and portable water testing, especially in low-resource settings. Moreover, blockchain ensures data integrity and transparency, supporting trust in multi-stakeholder systems. The chapter also discusses integration frameworks, ethical considerations, and global case studies—from smart urban water systems in Singapore and the Netherlands to community-based initiatives in India and Kenya. It concludes by emphasizing the importance of interdisciplinary collaboration, policy support, and inclusive technological deployment to advance global water security and meet Sustainable Development Goal 6. These innovations represent a paradigm shift in monitoring, offering robust tools for safeguarding water resources amidst growing environmental and societal challenges.