With no direct water source available, the water will evaporate in a filled tank within two to 10 hours of operation, depending on the water capacity of the evaporative cooler, ambient conditions, temperature and humidity. A water source for refilling the tank is recommended by the manufacturer. Most Portacool evaporative coolers can be connected to a standard garden hose and will self-regulate the water level with the use of a factory-installed internal float.
