Approximately how much of the water on earth is fresh water?
Water security population institute, asserts that although an overwhelming majority of the planet's surface is composed of water, 97% of this water is constituted of saltwater; the fresh water used to sustain humans is only 3% of the total amount of water on Earth. Therefore, Smith believes that the competition for water in an overpopulated world would pose a major threat to human stability, even going so far as to postulate apocalyptic world wars being fought over the control of thinning ice sheets and nearly desiccated reservoirs. Nevertheless, 2 billion people have supposedly gained access to a safe water source since 1990
Water distribution on Earth frequent and almost always not seriously considered when they were first developed. The total volume of water on Earth is estimated at 1.386 billion km³ (333 million cubic miles), with 97.5% being salt water and 2.5% being fresh water. Of the fresh water, only 0.3% is in liquid form on the surface. In addition, the lower mantle of inner earth may hold as much as 5 times more water than all surface water combined (all oceans, all lakes, all rivers). The total volume of water in rivers is estimated at 2,120 km³ (510 cubic miles), or 2% of the surface