The human body is made up largely of water. Up to 75% of our body is water. Water helps us digest food. Chemical reactions in our body would not be possible without water. It also needs water to help carry away the substances that we don't need any more. Water regulate our body temperature so that it always stays the same. Although we can live without food for a few weeks without water we would die within a few days. A normal human needs about 2 to 3 litres of water a day to survive. ( no copas!! )