83% of blood is made up of water. Water helps to digest food, take in oxygen, transport body waste and control temperature. Humans must replace 2.4 litres of water every day through either drinking or eating foods with a high water content. 70% of the worlds freshwater exists as ice in glaciers or ice caps. In a typical home, only 4% of water is used for drinking and cooking. Development of new towns and redevelopment in the Dublin city area has increased the projected water requirement in Ireland to more than double the supply available in 1970. There are approximately 2,700 km of watermain serving Dublin City, of this 40% are over 50 years old.