A related problem is water pollution. More than a billion people in the developing world lack safe drinking water. About half the world's population of six billion lacks access to adequate More than a billion people in the developing world lack safe drinking water. About half the world's population of six billion lacks access to adequate sanitation systems. From this perspective, the effective management of water resources is a crucial issue that must be tackled by government and private sectors throughout the world.
Saline water is used primarily as a coolant for industrial processes.
While water's uses are numerous, they may be generally classified as either consumptive or in-stream. When water is withdrawn from but not returned to a stream, lake, or aquifer, that process is referred to as consumptive use. A major example is agricultural irrigation. In-stream uses of water include such activities as navigation and hydroelectric power generation. In terms of total withdrawals, the largest proportion of water usage in the United States and many other countries is for cooling at thermal electric power plants.