Portacool Evaporative Coolers. Evaporative cooling technology dates back to the ancient Egyptians. At Portacool we have taken the process and made it more efficient and effective. Many companies brag that their products only use a few gallons of water a day. In reality, the more water an evaporative cooler uses the better it is working – meaning the more cool, refreshing air it is producing. Portacool evaporative coolers all come with a built in reservoir (ranging from 50 to 75 gallons) and hose connections for continuous feed, which means keeping the cool air coming for long periods of time is no problem.