This book provides a roadmap for sustainable development and growth of petroleum industry with respect to water usage and discharge. Water and energy are intricately tied with each other. As a major source of conventional energy, petroleum industries— upstream, midstream, and downstream—are collectively large consumers of water. Increasing water stress in major parts of the world has made the industry aware of the impact of usable water on different sectors of petroleum industry, e.g., exploration and production, refining and fuel processing. Treatment of wastewater effluents to maximize reuse is becoming a primary objective of the industry. This, coupled with the need to minimize discharge of contaminants in the effluents that affect human and aquatic life, and the environment at large at reasonable cost is emerging as an important consideration facing the petroleum industry for its sustainable development and growth in the future decades. This book discusses in detail: Sources of water consumed by petroleum production and processing, and wastewater produced Health and environmental effects of chemicals contained in effluent streams Effluent treatment processes—current and new innovations, and technologies for reuse