Water is a chemical substance with the formula of H2O. Also one oxygen and two hydrogen atoms are connected by covalent bonds. Earth is mostly made out of water. 70.9 percent of Earth's surface is covered in water. Water, not surprisingly, is mostly found in large bodies of water (Oceans). 1.6 percent of Earth's water is under ground. 0.001 percent of water is vapor, clouds and precipitation (rain). The oceans hold 97 percent of Earth's surface water. 2.4 percent of Earth's surface water is in glacier's and polar ice caps. 0.6 percent of surface water is in rivers, lakes and ponds.