Water is a chemical compound consisting of the elements oxygen and hydrogen. It is the only compound that can be found on earth in all three states of aggregation: Solid (ice), fluid and gaseous (steam).
Approximately 71 percent of the Earth's surface is covered by water. But roughly 96.5 percent of the entire water on Earth is undrinkable saltwater. Only about 3.5 percent is fresh water. Since most of this water (1.77 percent) is in a frozen state as polar ice and in glaciers, only about 1.7 percent of all the water is available as potential drinking water.