Some ways to visualize a million gallons of water.

A million gallons of water -- How much is it?

If you start browsing through the U.S. Geological Surveyu (USGS) water-use information, you'll see water withdrawals and use are most often reported in "million gallons per day" (Mgal/d). You'll understand the data better if you can visualize how much a million gallons of water is.