One of the main challenges faced by humans today is finding a balance between economic development of respective countries and sustainable utilisation of Earth’s resources. With the increase in the human population, demand for water resources is increasing globally. One of the challenges for water conservation in the future is the sustainability of current and future water resource allocation. Finding a balance between what is needed by humans and what is needed in the environment is an important step in the sustainability of water resources. With this in mind, sustainable utilisation of water resources, and conservation and management of aquatic ecosystems on Earth is an essential step towards the sustainable management of global water resources. This book discusses the current status of water resources on Earth and challenges water resource conservation in the first chapter. The second chapter of the book describes the physical, chemical and biological properties of water, and the biological indicators that can be used as water quality indicators. The third chapter of the book discusses how water becomes polluted, factors contributing to water pollution, as well as types and sources of water pollutants. The fourth chapter discusses the importance of water quality monitoring programmes and the methods of water quality monitoring programmes. Chapters Five and Six discuss the characteristics of lotic and lentic systems, factors affecting lotic and lentic systems and possible management options for each category. Chapter Seven discusses the aspects related to watershed management and water pollution control. The final chapter discusses agricultural and urban watershed management options, common issues related to their management, and strategies to reduce waste generation and pollution control.