Which best describes the amount of Earth’s total water supply that is usable freshwater?

The amount of Earth's total water supply that is usable freshwater is quite small. Here's a step-by-step breakdown:

1. Total water on Earth: This includes all the water in the oceans, ice caps, lakes, rivers, groundwater, atmospheric water, and even the water in you, your dog, and your tomato plant.

2. Saltwater vs Freshwater: About 97.5% of all water on Earth is saltwater, leaving only 2.5% as freshwater.

3. Accessible Freshwater: However, not all of this freshwater is easily accessible or usable. Over 68% of it is trapped in ice caps and glaciers, and less than 30% is in the ground.

4. Usable Freshwater: Only about 0.3% of our freshwater is found in the surface water of lakes, rivers, and swamps.

So, in conclusion, the amount of Earth's total water supply that is usable freshwater is less than 1%.