When cooling, Wave produces excess water. What makes Wave unique is that it takes this excess water and sprays it on the internal condenser to evaporate it (which runs hot while in use) without manual drainage.
In high humidity environments (70%+ humidity) you may find excess water building up. Here, you can use the drain hole to empty your Wave when you’re done using it and need to transport it. If you’re in low to medium humidity, this won’t be an issue.