BD,
Guess I'll start the ball rolling...
Can you get away with it? Are you asking from the legal (permits) standpoint or more so from an "engineering" standpoint?
I'll comment on the latter, and don't know about the former. It depends on your annual rainfall, your soil conditions, and the watershed. There aren't absolute answers. Some areas require lots of watershed, some you can just dig a hole in the ground and wait for it to fill up.
