how much is actually is salt water on earth
Water distribution on Earth - Distribution of saline and fresh water. 1  The total volume of water on Earth is estimated at 1.386 billion kmÂ³ (333 million cubic miles), with 97.5% being salt water and 2.5% being fresh water. 2  The total volume of water in rivers is estimated at 2,120 kmÂ³ (510 cubic miles), or 2% of the surface fresh water on Earth.