I too am investigating my property to establish a rainwater catchment system. My interest in this is several reasons: I don't want to overly rely on our community aquifer, I don't want to use the irrigation system in our yard, I would love to feed something in our yard that can sustain my family, and I would like my kids to play in the water sometimes and not feel awful about wasting it.  

I am looking at Intermediate bulk containers (IBC) to catch the rain off the back of the house and a smaller barrel on the side and front of the house.  Has anyone used IBC's? I assume they are just like any rain barrel system. 

The plan is to place the barrels under the deck then possibly dig trenches and swales to catch any additional overflow from the system which would feed the garden below.