Step 1: Recycle instead of dump
I decided to recirculate the water back into the humidifier instead of dumping it.
Start with two 5-gallon buckets. Tape the buckets together, bottom-to-bottom, and drill a pilot hole through the bottoms of both buckets. You might also want to remove the handle on the bottom bucket because it tends to get in the way.
Now pull the buckets apart and use the pilot hole to drill a 1" hole in the top bucket and a 2" hole in the bottom bucket. Also drill another 1" hole in the side of the bottom bucket about 5" from the bottom. Check out pictures in the next steps first and you will see why these holes go where they do.