About 2.5% of all the water on Earth is freshwater, with the remaining 97.5% being saltwater primarily in the oceans

. The total volume of water on Earth is estimated at approximately 1.386 billion cubic kilometers, so freshwater accounts for roughly 34.65 million cubic kilometers of this total

. However, most of this freshwater is not readily accessible for human use. About 68.7% of Earth's freshwater is locked up in glaciers and ice caps, and a large portion is also stored as groundwater

. Only about 1.2% of all freshwater is surface water, which includes water in lakes, rivers, and swamps, and this is the portion that primarily supports terrestrial life

. Breaking down the surface freshwater further:

• Lakes hold about 87% of surface freshwater.
• Swamps contain about 11%.
• Rivers make up only about 0.49% of surface freshwater, yet rivers are a critical source of freshwater for humans

In summary, while Earth has a vast amount of water, only a small fraction- about 2.5%-is freshwater, and an even smaller fraction of that is easily accessible for human and ecological use