You start with some circle (or square, etc.) whose area represents the total amount of water, and you color the fraction that is fresh. Then you draw lines guiding the eye from the small colored spot to another large circle (etc.) which now represents the fresh water, and you color the fraction that is groundwater. And then repeat.

I’ve seen this done before, and I think it’s as good as any other method I’ve seen for helping people visualize repeatedly taking small fractions.

The National Geographic bit is nicely done, and tells a different story:
- they also say 97.5% is salt water, 2.5% fresh (agree)
- of that 2.5%, 60% is ice, 10% is surface water, like lakes and rivers, and 30% is groundwater (but some too deep to get at) (why does this graphic lump surface water–a major source of the water we use–with ice?)
- 70% agricultural, 22% industrial, 8% “pumped into cities for drinking, washing and watering” (how does 8% turn into 0.08%? some earlier commenters noticed it, but that’s a two orders of magnitude error in the punch line!)

National Geographic doesn’t attempt to say how much of the 40% of unfrozen fresh water is used for agriculture, industry and domestic purposes, so the 1% in the graphic comes from somewhere else.

So partly it looks like there are two loosely connected stories here: one about where water is distributed on the planet, and the other about human use of water. Each story is clear by itself, but I don’t understand what I’m supposed to get from the connection.

Thank you so much for taking note of our graphic and inviting your community to offer feedback. The comments here so far are great and will be useful for us on future graphics. I would love to work with you to build a new graphic to build on the thoughts shared here. Please email me if you’d be interested in collaborating. We would update our post with the new graphic and tell the story about how you and your readers helped us in that process.

I’m also working on a post to put on TreeHugger that will point to yours and invite additional comments on the graphic.

Cheers,
Chris Tackett
Social Media Editor
TreeHugger.com

All leading to the conclusion that a small proportion of all fresh water is available for domestic use – so why start with all water on Earth?

Of course, fixing the graphic wouldn’t cause the premise to make sense. Implicitly, it says that the amount of currently potable water is what matters, but both humans and mother nature create potable water from non-potable water all the time. So water supply for human domestic use is not a stock, it’s a flow.