Can i use deionized water instead of distilled water
Water from a dehumidifier is similar to distilled, in that it contains little in the way of dissolved materials.   It condensed on (typically) anodized aluminum,
and dripped through polymer collection trays into a bucket.  

How clean is the bucket?  There may be residue from dust/lint etc.

It's water.   You can moisten plants, fish can swim in it, and it's pure enough
to drink or wash your windows (in fact, it's softer than most tap water, it
makes a good final rinse for windows).  I'd stick to deionized or distilled
for lab use, though, because those didn't come from a dirty bucket.