A regular portable AC unit does not require filling of any sort. In contrast, it necessitates drainage to keep up a cooling effect. However, an evaporative portable AC is different. How is it different? It has a water tank and an icebox. They should be filled and refilled for the AC function. Evaporative or humidifying portable ACs do not need window installation. Regular portable ACs have a hose attachment that joins the units to the window. What is the function of the hose? It exhausts tainted air present in the room outside. Evaporative units do not require a hose. Regular portable ACs attract moisture from the air, while evaporative units utilize moisture to cool a room. Evaporative units have an internal tank that users must fill with water. Regular portable ACs also have an internal tank. However, users need to empty it to make the ACs work right.