South Asia, covering 3% of the world’s total landmass, is home to about 25% of the global population, making it the most densely populated region on Earth. Despite this demographic pressure, the region holds only 5% of the world’s annual water resources, which are spatially and temporally unevenly distributed. As South Asia experiences rapid population growth and urbanization, it also faces a range of environmental and political challenges, including rugged terrain, frequent floods, recurring droughts, and political instability. These factors underscore the urgent need for effective water resource management to support sustainable development and livelihoods. Given the diverse challenges and needs across the eight countries of the region, South Asia has developed a broad array of water-related policies, regulations, acts, and institutions. This chapter offers a comprehensive review of these legislative frameworks to support improved planning and sustainable water management for future generations. Historically, as an agrarian society, the region’s early water policies focused primarily on irrigation management. Over time, the scope of these policies has expanded to include issues of water accessibility, hydropower development, and supply management. Today, new challenges, such as water quality, sanitation, and pollution control, demand further policy evolution. The rural–urban divide across all South Asian countries further complicates water management, necessitating customized approaches. Countries like India and Bangladesh have responded by formulating distinct policies and establishing specialized institutions to address the varying needs of rural and urban populations. These evolving frameworks highlight the ongoing efforts of South Asian nations to ensure sustainable water resource management while addressing emerging challenges posed by population growth, urbanization, and climate change.