Water resources

Water resources are natural resources of water that are potentially useful for humans. For example, they serve as a source of drinking water or irrigation water. These resources may consist of freshwater from natural sources or water produced artificially from other sources, such as reclaimed water (wastewater) or desalinated water (seawater). Approximately 97% of the water on Earth is salt water, and only 3% is fresh water; slightly over two-thirds of this is frozen in glaciers and polar ice caps. The remaining unfrozen freshwater is found mainly as groundwater, with only a small fraction present above ground or in the air. Natural sources of fresh water include frozen water, groundwater, surface water, and under river flow. People use water resources for agricultural, household, and industrial activities. Water resources are under threat from multiple issues. There is water scarcity, water pollution, water conflict, and climate change. Fresh water is in principle a renewable resource. However, the world's supply of groundwater is steadily decreasing. Groundwater depletion (or overdrafting) is occurring for example in Asia, South America and North America.