Abstract: A transportation system for liquid-carrying tanks. Each tank is mounted on a carrier unit and plural carrier units are transported by a single trailer or other vehicle. The trailer has an adjustable height, while each of the tank carrier units has adjustable height legs on its opposite sides. The units are loaded by backing the trailer under the carrier unit with the carrier unit legs extended and the trailer lowered. The trailer is then raised to lift the carrier unit to a transport position and the legs are in turn lifted to the transport position. For unloading, the reverse procedure is adopted, with the carrier unit legs being lowered to the ground and then the trailer being lowered and the trailer being pulled out from under the carrier unit. The carrier units are arranged with an angled base so that when the carrier is pulled out, the carrier unit will tilt forwardly to provide maximum drainage of the tank.