Chicago uses one billion gallons of water a day, the vast majority of which is processed at the James W. Jardine Water Purification Plant, the largest treatment plant in the world. (You'd recognize it from its trademark "cribs," those little houses floating out in the lake you can see from the beach.) But there's much more to it than that, including hundred-year-old tunnels buried 16 stories below the lake big enough to drive a Model T through. If you've got two minutes, read this post about Chicago's water-processing system, and if you've got ten, watch the video embedded in it. Water you waiting for??