A small drip from a tap can waste as much as 75 litres of water a day. Posted on August 30, 2011 by Lindsay Wakelin Human brains are 75% water. Human bones are 25% water. Human blood is 83% water. 75% of a chicken is water. 80% of a pineapple is water. 95% of a tomato is water. 70% of an elephant is water.