The focus of the book is on scientific tools, methodologies and technologies available in the country today to address water issues; additionally, chapters in the book also typically present relevant policy interventions. The book opens with an overview of the current status of surface and ground water resources in the country. Subsequent chapters cover tools for estimation, measurement and monitoring of water resources at various temporal and spatial scales. Snow and glacier hydrology, isotope techniques, groundwater prospecting and applications of remote sensing are covered in detail in individual chapters. Considerable progress has been achieved in the country in the fields of wastewater treatment technologies and desalination of seawater and brackish water to generate new sources of water. In the current and evolving scenarios of acute water shortages in various parts of India, improving water-use efficiencies in coupled agriculture-climate systems and urban water distribution emerge as important themes to optimally utilise the available resources. The book details the existing knowledge in each of these areas. On a larger scale, hydrologic extremes such as floods and droughts, river sedimentation and climate change impacts on water resources are also reviewed. The book concludes with a chapter on broad-level recommendations for policy interventions needed in the water sector. The language in the chapters is kept simple and non-technical to the extent possible, to make it appealing to the general reader.