This Scientific American article by Mark Fischetti and infographic by Jen Christiansen detail the consumption of water usage throughout the world. Jen used a Sankey diagram to show the top 10 water consuming countries and how their water was being used. One of Mark's first points in the article is that population is the largest factor of water consumption. So I wonder why population adjusted numbers weren't used. Many of the article's commenters felt the same way. One posted a few of the countries per capita water use:
China: 2781 lts/day, India: 2591 lts/day, US: 7175 lts/day, Japan: 3752 lts/day
The way you display your data depends on the story you're trying to tell. In this case, I wonder if the message could be better by using per capita.