Water resources are natural resources of water that are potentially useful. Uses of water include agricultural, industrial, household, recreational and environmental activities. All living things require water to grow and reproduce. 97% of the water on the Earth is salt water and only three percent 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. Fresh water is a renewable resource, yet the world's supply of groundwater is steadily decreasing, with depletion occurring most prominently in Asia, South America and North America, although it is still unclear how much natural renewal balances this usage, and whether ecosystems are threatened. There are several principal manifestations of the water crisis. Inadequate access to safe drinking water for about 884 million people Inadequate access to sanitation for 2.5 billion people which often leads to water pollution Groundwater overdrafting (excessive use) leading to diminished agricultural yields Overuse and pollution of water resources harming biodiversity Regional conflicts over scarce water resources sometimes resulting in warfare.