One acre-foot of water weighs approximately how many pounds?

• A. 1.0 million
• B. 2.7 million
• C. 5.4 million
• D. 10 million

Answer: (B)

Understanding the weight of a common water measure helps with field calculations. An acre-foot is the volume of water covering one acre to a depth of one foot. That volume is 43,560 cubic feet (since one acre equals 43,560 ft², times 1 ft deep).

Water weighs about 62.4 pounds per cubic foot. Multiply the volume by this density: 43,560 × 62.4 ≈ 2,718,000 pounds, which rounds to about 2.7 million pounds.

So the weight of one acre-foot of water is roughly 2.7 million pounds. The other numbers would require altering the volume or the density beyond the standard values used here.