DD is right on with his info....I used to raise them when I was a kid. It was actually my first business venture that I undertook seriously. My dad raised rabbits at the time, and I thought it would be a good thing for me to try and make use of that situation. I set up wood boxes under the cages for the worms.

I never had a problem sorting them out. I used a screen that would let the soil/material sift thru, but small enough to hold the worms back. Never had to use water to do it. Suppose it all depends on the material they are kept in.