Of all the available water on the planet, how much is fresh water?

• A. 2.5%
• B. 0.3%
• C. 0.2%
• D. 3%

Answer: (B)

The key idea here is how much of Earth’s water is both freshwater and readily usable. Most of our planet’s water is salty ocean water, which isn’t drinkable or directly usable for most needs. Freshwater makes up only a small fraction of all water. Even within that small slice, much is tied up in glaciers, ice caps, and deep groundwater, leaving only a tiny portion in rivers, lakes, and near-surface groundwater that we can easily access. That readily usable freshwater accounts for about 0.3% of all the water on Earth. So, among all the planet’s water, roughly three-tenths of a percent is fresh water that’s practically available.