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Natural Water Resources of the World

Water is vital for bathing, cleaning, cooking, filling our swimming pools, watering our gardens and lawns, irrigation, maintaining public parks, sewer and wastewater treatment and recreation. Water access is a problem for many areas of the world: more people worldwide own a cell phone than have access to a toilet. Despite two-thirds of the planet's surface being covered with water, only 2.5 percent is freshwater. This problem is exacerbated by drought and climate change.

Lakes and Streams
- Lakes and streams, called surface water by the U.S. Geological Survey, provide water for most of our uses. In many areas of the United States and worldwide, stream runoff is down considerably. For example, the once mighty Rio Grande river that separates Texas from Mexico is down to a muddy trickle in many areas because of damming for hydroelectric power. Even large river basins like the Amazon and that Congo-Zaire are affected by seasonal fluctuation and cannot be counted on to supply all the water needs of their surrounding communities indefinitely.
Aquifers
- Much accessible freshwater is underground in aquifers. Worldwide, groundwater resources are used for the majority of urban water needs. The Oglalla, or High Plains Aquifer, is one of the largest aquifers in the world and it supplies the majority of the water to the middle states in the U.S. stretching from South Dakota to Texas. Currently, the water is being withdrawn from the aquifer at a rate of up to 50 times faster than it can be withdrawn, which may eventually make it an unsuitable source for irrigation and large-scale water uses in cities.
Oceans
- The oceans are the largest sources of water. Seawater can be treated and turned into freshwater, a process called desalination, but the technology is prohibitively expensive and impractical for large scale use. However, desalination plants do exist, mainly in dry areas of the world. Middle Eastern countries account for 70 percent of the freshwater production from these plants. The amount of water produced from desalination is very small, however: only 1 percent of the world's freshwater comes from saltwater.
Polar Ice Caps
- Glaciers and the polar ice caps contain 69 percent of the world's freshwater resources. Many climatologists are concerned that the melting of the polar ice caps because of warming trends will result in higher sea levels and less freshwater for human use worldwide. In addition to the loss of freshwater, this massive melting of water can raise the sea levels and make the water less saline, which will have a direct effect on marine life.

Nature