Clark W. Griswold, Jr. wrote:
What????? If you have standing water in the coil, you have far more
than humidity problems. That's why they have drains...

It is the water evaporating from the coil (and yes, the drain area) that
causes the increased humidity. Read the linked article below for more
information.
http://www.fsec.ucf.edu/bldg/pubs/pf118/index.htm