Those are great photos of one barrel linking to the next, Paul! We have several linked up together and plan to run one entire side of the house in barrels. We already have at least one barrel on every downspout and two on more "active" spouts. It's amazing how much water you can fill in a short rain. Typically a 15 minute medium rain garners us about 600 gallons.
I try to stretch it out between rains!