Short answers, pulled from the story.
Only 2.5% of Earth's estimated 1.386 billion cubic kilometres of water is fresh, while 97.5% is saline. Of that fresh water, only 0.3% exists as liquid on the surface. Most fresh water is locked in ice and glaciers.
Most of Earth's fresh water is locked in ice and glaciers. The Antarctic ice sheet alone holds 21.6 million cubic kilometres, representing 61.7% of all fresh water on the planet. The Greenland ice sheet accounts for another 6.68%.
The African Great Lakes collectively hold 30,070 km3 of fresh water, the largest volume of any lake group. Lake Baikal in Siberia contains 23,615 km3, and the North American Great Lakes hold 22,115 km3, representing 21% of the world's fresh water by volume.
Soils in Australia and Southern Africa have been largely unaltered since at least the early Cretaceous, leaving them nutrient-poor. Native plants compensate with dense root systems, including proteoid roots, that absorb so much water that runoff typically does not begin until about 300 mm of rainfall has fallen. Temperate and arid rivers there show as much as three times the coefficient of variation of runoff compared to rivers in similar climates on other continents.
Earth's rivers hold an estimated total volume of 2,120 km3, which equals 0.49% of all surface fresh water. Asia generates the largest share of global river runoff at 13,300 km3 per year, followed by South America at 12,000 km3 annually.
Direct evidence of water in Earth's mantle was confirmed in 2014, based on a hydrous ringwoodite sample found enclosed in a diamond from Juína, Brazil. Scientists estimate that 1.5 to 11 times the volume of all surface oceans may be stored inside Earth's interior, though the precise total remains under debate.