I'm with CK on this, but others aren't. It's almost like the 18/6 vs 24/0 debate, but if you've ever cleaned off refrigerant coils, that might change your mind.This is just my thoughts but...
The water collected by a dehumidifier isn't pure, and it's probably best just to pour it down the drain. The water comes from condensate on refrigerant-type coils and it collects in a basin. The water washes dust out of the dehumidifier as it drips into the collection basin, where it also collects dirt.
Fish breeders won't use dehumidifier water in aquariums because fish don't breed well in it, possibly because copper or zinc collects in the water from the condensation coils. Watering plants may be the safest re-use of this water, however the minerals may be an issue there, too.
Someone else may have a differing opinion.. that's all I am offering here!