A Million Gallons of Water - How much is it?

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If you look at our U.S. Geological Survey (USGS) water-use data, you see it is presented in "million gallons per day" (Mgal/d). We will help you visualize how much a millions gallon is so you can better understand our water-use information.

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A Million Gallons of Water -- How Much is it?

A million gallons is a cube 51.1 feet on each side.

If you start browsing through 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. A good-sized bath holds 40 gallons, so a million gallons would be 25,000 baths. But, it might be easier to take a look at the pool and cube image.

If you were a swimming-pool builder and a customer asked you to build a pool that would hold a million-gallons, then they had better have a big yard! You would need to build a pool about 267 feet long (almost as long as a football field), 50 feet wide, and 10 feet deep. The cube on the right side shows you that 1 million gallons would form a cube that is 51.1 feet on each side.

Some helpful conversions:

  • 1 Mgal/d = 1.547 cubic feet per second
  • 1 Mgal/d = 694.4 gallons per minute
  • 1 Mgal/d = 1.121 thousand acre-feet per year
  • 1 million gallons = 3,785,412 liters
  • 1 million gallons = 3.07 acre feet



    How much do you think a million gallons (3,785,412 liters) of water weighs?

    •  At 8.34 pounds per gallon, a million gallons comes in at 8,340,000 pounds.

    •  At 1 kilogram per liter, 3,785,412 liters comes in at 3,785,412 kilograms.