You will find that you drain your portable air conditioner anywhere from every 8 hours to once a month. The frequency of when to drain your portable air conditioner highly depends on its usage, its quality, and capacity of its internal reservoir. Combining these will give you the ideal frequency when you should drain your water. When you begin using the unit when it is new, you may experience some difficulty gauging the frequency. Thus, you will end up with a full tank from time to time, but over time, you will eventually get a hang of it.