[1][2][3] The device is also called a water column in the United States and Australia.Generally, water cranes consist of an upright steel pipe about 8 to 12 inches (0.20 to 0.30 m) in diameter with a horizontal, pivoting pipe connected to its upper end so as to form a swinging arm.[7] In flatter country this arrangement is not always possible, so water may be supplied by a tank next to the crane.[8] Depending on the quality of the water under supply, it may need to be treated chemically to eliminate hardness which induces scale buildup on the inside of the locomotive boiler.[5] The scale which builds up on heat transfer surfaces forms a layer of insulation between the metal of the firebox and the boiler water.