Water consumption varies greatly among regions due to differences in economic development. The average municipal use in the United States is about 150 gal (568 l) per person per day, though the rate can be higher than 350 gal (1324 l) in some locations. This includes home use for bathing, waste disposal, and gardening, as well as institutional and commercial usage. Per capita (per person) water usage in Asia is only 22 gal (85 l) per day, and just 12 gal (47 l) in Africa.
According to the World Health Organization (WHO) of the United Nations,people have a minimum water requirement of about 5 gal(20 l) per person perday.This is the minimum amount needed for physiological rehydration, cooking, washing, and other subsistence requirements. However, the WHO estimates that nearly two billion people consume contaminated water. This carries a significantrisk of developing such water-borne diseases as cholera, dysentery, polio, or typhoid, which kill about 25 million people per year. Both conservation and sanitation are obvious necessities in meeting the huge demand for freshwater.Because irrigation accounts for 70% of the water used by humans worldwide, achieving a better efficiency of agricultural use is a logical step in advancing water conservation. This can be accomplished by lining water delivery systems with concrete or other impervious materials to minimize loss by leaking during transport, and by using drip-irrigation systems to minimize losses by evaporation. Drip-irrigation systems have been successfully used on fruit trees,
certain row-crops, and horticultural plants. Conservation can also be accomplished by improving the efficiency of utilization of water by crops, including the cultivation of plants that are less demandingof moisture.
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