Ninety-eight percent of the water on the planet is in the oceans, and therefore, is unusable for drinking because of the salt. There are processes that can remove the salt, but they are difficult and expensive.
About 1.6 percent of the planet's water is locked up in polar ice caps and glaciers in the North and South Poles. The water found there is fresh water and can be melted; however, the long-term effects of this could be detrimental.
About 0.4 percent of all the water on Earth is freshwater that is usable. A large part of this is found in aquifers and wells. Only about .04 percent of the planet’s water is found in rivers and lakes. Even that small of a percentage is still thousands of trillions of gallons of water, but it is a very small amount compared to all the water available.