The percentages of fresh and saline water have also changed over time. Today, there are about 300 million cubic miles(1.3 trillion cubic kilometers)of H2O on earth. Approximately ninety seven percent of that exists in ocean. Only around three percent of earth's water is fresh enough to drink, and nearly half of that is frozen. Fresh,drinkable water in lakes and rivers is not available in every location. Over forty percent of our drinkable water is located in lakes in the United States and Siberia