Product review (5 stars): kind of like a refrigerator
I have had this icemaker for 4.5 months now.  I only use "Zero" water in it.  If I shut it off at night it eventually builds up a little bit of mold, so I keep it on 24/7 and it works perfectly.  Since the ice is what keeps the holding area cold that seems to be what keeps the mold away, kind of like a refrigerator.  I love it and would buy again.