Just how scarce is potable water on this Earth? We learn in school that more than two-thirds of the planet is covered in water. But that figure is deceptive because it refers to just surface area, and describes only the total quantity of undrinkable salt-water.

The truth about just how little water we have to go around is just about crystal clear in this graphic from the U.S. Geological Survey, courtesy of my wife’s father Raj Bhattarai, regulatory manager of the Austin, Texas water utility.

See the big blue bubble? That’s the volume of total water on the planet (salt and fresh water), to scale. The second little blue ball is the total amount of fresh water on the planet. The tiny little blue spec under that one – that’s the amount of fresh water currently accessible to humans. Turn off those faucets, y’all.