OK, let's get series here and tell me how hugh your barrel is, will you collect runoff from your roof and will you dip from the barrel or is it large enough for a bung near the bottom to put a spigot in and connect a hose to?
I have two rainspot locations that I thought I would put a series of 2-3 barrels each location to allow overflow from one to the other and the gravity feed from barrel into my drip lines...