I drink out of a sippy cup so that dust doesn't fall in my water.
EDIT:
Before some stoner actually does drink their dehumidifer water, stagnant condensate can harbor a myriad of contaminants, including mold, mildew, algae, lead and other metal residues from the components of the dehumidifier. Unlike distilled water, dehumidifier water is never sterilized through boiling. In case you were still entertaining the thought, let me make it clear: do not drink the condensate!
But back to the topic... watering your plants, not drinking it.
I'm not saying using gray water to water your cannabis is the best idea, but it probably won't negatively affect your plants if the bucket is cleaned regularly.