The classic way to convey the error that exists in a measurement is a formula that shows the obtained measurement (X) as a sum of a true score plus some error. One version of this formula is: X = T + e. With this formula in mind, obtaining more precise measures depends on reducing error.
  Mega is the prefix meaning one million, therefore there are one million (1,000,000) gallons in a mega gallon.
Quick Answer. There are 31.75 gallons in 1 ton of water. A ton is equal to 2,000 pounds and each gallon is composed of 8.33 pounds; a gallon measures the amount of liquid volume of a substance while a ton measures the true weight of a substance.