This chapter explores the coal–water nexus with evaluation of the chemical hazards in coals and the magnitude of their emission with coal combustion, the quantity of water use for coal mining and processing and implications for water quality, with an emphasis of the formation of coal mine effluents such as acid mine drainage and the large water-impaired intensity. The chapter describes the different technologies for cooling thermoelectric plants and the associated water intensity and thermal pollution upon the discharge of the cooling water to the hydrosphere. The chapter explores the formation of coal combustion residuals after coal combustion, the enrichment of contaminants in coal combustion residuals, and the volume and quality of effluents associated with coal ash impoundments, and the environmental risks associated with the management of coal ash and leaking coal ash impoundments. Finally, the chapter looks at the different regulations in different countries with respect to coal mining, combustion, and disposal, as well as the transition from coal to different energy sources.