The drainage system is a ~1-inch deep “tray” in the bottom of the bin, covered with a fine screen (actually some sheer polyester fabric). All the composting action happens above the screen, but if it becomes oversaturated then water should drain through the screen into the bottom.
I also added a sealable spout for easy draining of the excess water, by repurposing the top of a plastic soda bottle and using tons of silicone.
I bought 1/4 pound of red wigglers from a very nice local woman selling worms from her own composting system, but realized it would take too long for them to repopulate to fill the bin. So I re-upped with another half pound or so from a live bait shop. Hopefully the hippie organic worms will get along with the more rough-around-the-edges bait worms.
I’ve been slowly ramping up feeding them scraps this week, and will be figuring out what a good steady-state amount to feed them while they grow into the container. But I think they’re happy so far.
For anyone considering setting up a vermicomposting system like this, I highly recommend reading Red Worm Composting. It’s a great combination of anecdotes and more scientific information about this style of composting.