On cooling you don’t have to empty the water tank (there is no water tank actually but there is a hose output and you can use your own bottle or tank, when in dehumidifier mode). On cooling mode it’s using the water collected to cool down the warm condenser which then flows outside through the air hose.

There is no need to empty the water tank, the moisture evaporates and is not stored in the tank

I haven't used it yet I'm sorry