M-149 Water Buffalo, a 400-gallon steel tank sitting on a trailer chassis, Joint Base Andrews, MD, May 2011.
Military vehicle trailers for fuel and water consist of a tank mounted on a chassis. The capacity of the tank may be small or large depending on the intended use of the trailer. For example, the trailer tank may hold a few hundred gallons of water to supply a small unit in the field. Or the tank may hold thousands of gallons of jet fuel for use in refueling aircraft at an air base. Since the word tank is ambigious, these trailers must be distinguished from trailers whose purpose is to carry or retrieve armored vehicles (e.g. M4 Sherman tank).