Free is for me, and so if I can get free water for my plants, I will do it. I also get 55 gallon barrels from my work, so that is even better! To the right is the set up I have at southeast corner of my house. Our house is ranch-style from the front, but with a built out basement, so it is two levels in the back. That means there is a significant drop in elevation from the front to the back I get a really good flow of water from these barrels. I set this up around August and I get a really good flow of water from these barrels.
Basically I just cut a 6″ hole in the top and put a circular drain cover on it. I might add a screen to the underside to keep out the big particles, if need be. This worked fine. I cut a 1/2″ hole in the top side and added some pvc connector with rubber gaskets. I screwed in a 5/8″ brass hose connector. I would have preferred a plastic one, as it is cheaper, but I could not find one. I had an old hose that I cut and attached. This is for the overflow, but I have it going into another barrel. I have a total of 4 barrels in this spot (~200 gallons), and with a good rain I can get 50-100 gallons or more. At the bottom I cut 1-1/2″ hole (if I remember correctly) and got a connector with gaskets (~$11) with a 1/2″ thread for the brass spout. In the spring I want to connect all four barrels into one central hose to use down in the garden.
I also have another three barrels coming off the main spout on my back deck. It looks a little less haphazard as my other four. The overflow drips directly to the barrel below, so I am saving on buying the brass hose barbs. The flow, however, is not as strong. I will either use this to flow into soaker hoses or build the blocks up higher for a stronger gravity feed.
I do have plans for three other parts of the yard. One is by the west garden and would feed that. The down spout is higher up from the back yard, so it should have a suitable flow. The others are at the front of the house, where I want to build more raised beds for flowers, herbs and vegetables.