Fresh Water in One Jug

A common educational analogy compresses all of Earth’s water into a four-liter jug: water considered available for use would then amount to roughly a spoonful. The result depends on what counts as “available” freshwater. The U.S. Bureau of Reclamation estimates that about 0.5% of Earth’s total water is available freshwater—20 mL in a 4-liter jug, or about 1⅓ tablespoons; actual access and usability vary.