During the cooling process, water is taken out of the air. This makes the portable air conditioner yield a condensation effect. Hence, all portable ACs remove water from the air as they work.
There are numerous and varying ways that different PAC units deal with water brought about by condensation.
With a simple unit, it would make use of a built-in water reservoir that would require emptying or draining on a regular basis with the use of a hose, probably as frequently as every 12 hours or just about once a week, as it is dependent on the degree of moisture that accumulate in the particular room. The water reservoir comes with a built-in auto-off feature to make sure no water is unintentionally leaked to the ground.
An advanced PAC, on the other hand, has a built-in evaporative technology that can vaporize large amount of accumulated moisture using a hot-air discharge feature. Therefore, there is a lesser amount of water (or none at all) that needs any draining.
All of the PAC units have some kind of the evaporative process of releasing moisture via an exhaust vent, but only a more sophisticated portable AC unit has the capability to totally remove the need of emptying or draining the water reservoir due to innovative features.
Other PACs have a water draining system that enables continuous draining of accumulated water using a drip pan. Alternatively, a gravity drain can also be employed by connecting a hose to the reservoir.