Where is Earth’s water?
Earth holds about 1.386 billion cubic kilometres of water. Only 2.5% is fresh, most of that is frozen, and the liquid fresh water at the surface is a rounding error on the total.
Earth is a water planet by area and a remarkably dry one by usable volume. The total is enormous — roughly 1.386 billion cubic kilometres — but the fraction available to drink, irrigate with or run an economy on is astonishingly small.
The full breakdown
The oceans hold 96.5% of all water on Earth. Add saline groundwater and salt lakes and the saline share reaches about 97.5%. Everything else — every glacier, every aquifer, every lake, every river, every cloud and every living thing — shares the remaining 2.5%.
View the data behind this chart
| Component | Value (km³) | Share | Notes |
|---|
Why so little is actually available
The 2.5% that is fresh is not 2.5% that is usable. More than two thirds of it is frozen in the Antarctic and Greenland ice sheets and in mountain glaciers — real water, but not where anyone lives and not accessible at any sensible cost. Almost all of the rest is groundwater, and much of that lies too deep to reach economically or is not being replenished.
What remains — the lakes, rivers, wetlands and shallow groundwater that human civilisation actually runs on — is well under one percent of one percent of Earth’s water.
| Step | Share of all Earth’s water | Why it drops |
|---|---|---|
| All water on Earth | 100% | — |
| Fresh water only | 2.53% | Removes the oceans and saline groundwater |
| Fresh and unfrozen | 0.79% | Removes ice caps, glaciers and permafrost |
| Fresh surface water | 0.0075% | Removes deep and inaccessible groundwater |
| Rivers alone | 0.00015% | The store most human use is drawn from |
Percentages derived from the volumes on this page. Rounded.
Why rivers matter so much despite holding almost nothing
Rivers hold about 2,120 cubic kilometres of water at any instant — roughly two ten-thousandths of one percent of the global total. Yet most of the water people abstract comes from them. The reason is that a river is not a store, it is a flow.
The water in a river is replaced roughly every two to three weeks. Over a year, the same modest standing volume delivers something like forty thousand cubic kilometres of water past the world’s river mouths. A reservoir with a fixed volume can be emptied; a river keeps arriving. This is the single most important distinction in water resources, and it explains why "how much water is there" is almost always the wrong question and "how fast is it being renewed" is the right one.
Frequently asked
Is Earth losing water?
Not in any way that matters on human timescales. A small amount of hydrogen escapes to space and a small amount is released from the mantle by volcanism, and the two roughly balance. The total has been broadly stable for billions of years. What changes is where the water is and what state it is in.
Could we just melt the ice caps for fresh water?
The volume is real — about 24 million cubic kilometres — but it is in Antarctica and Greenland, and melting it would raise sea level by around 65 metres. Towing icebergs has been proposed repeatedly and never made economic sense against desalination.
Is there more water in the atmosphere or in rivers?
The atmosphere, by roughly six times: about 12,900 km³ against 2,120 km³. The atmosphere turns over about once every nine days, which is why it can deliver all of the world’s precipitation while holding so little at any moment.
How much of Earth’s water can we actually drink?
There is no single number, because accessibility is economic rather than physical. The commonly quoted figure of under 1% refers to fresh liquid water that is not deep groundwater. Desalination technically makes 97% of Earth’s water drinkable, at an energy cost.
Sources
- United States Geological Survey — Water Science School — Earth’s water distribution. Open · US Government work — public domain
- UNESCO World Water Assessment Programme — United Nations World Water Development Report. Open — attribution required · CC BY-SA 4.0