Here's a photo of our setup, 4 of the square 50-gallon Rubbermaid barrels, set up on cement blocks and planks. We found some PVC parts to use to link them -- you can buy linking kits, but the tube seemed too small to handle the water flow -- and can easily disassemble them for winter storage. There's a runoff pipe on the 4th (right-side) barrel that empties into a runoff drain. (In the photo there's a piece of board sitting on top of the drain, everything wasn't quite finished when I took this pic.)
The tops have a window-screen type of insert that keeps most debris and such from getting into the barrels, although the granules from our roof shingles can get through. There are short hoses coming off the bottom of each barrel, which make it easy to fill watering cans; for direct watering on the garden we've been using a small pump, which is kind of a hassle and I think we might try adding an extra row of the cement blocks for a little more height next year, in hopes of being able to use the soaker hoses directly from the barrels.
