We attached a section of garden hose to the barbed fitting at the top of the barrel. This lets the rain water flow out of the barrel when it becomes full rather than overflow the top of the barrel. By attaching the hose, we can direct the overflow where we want it to go. In this case, it is towards a small spruce tree and towards a downward slope away from the garden shed.
Another option would be to add a second barrel and connect the two barrels using the overflow hose from the first barrel to fill the second barrel. This configuration would be beneficial in areas that get very little rain and have the need to harvest as much of the rain as possible.
Because we know that more rain is on the way this weekend we have flipped the diverter into the normal winter position which allows the rain water to flow out the downspout in a normal fashion. We figured that since the barrel is full and everything is thoroughly watered due to the rain, the barrel will still be full when the rain starts up this weekend thanks to the Tropical Storm that made landfall in Texas.
It took three rain storms to fill the rain barrel. The roof on the garden shed is small compared to the roof on the barn so I can only imagine how much rain water we should be able to harvest off the barn roof. Our plan is to install 3 rain barrels, one on three of the four corners of the barn.
So far we have been pleased with the ease of set up, the appearance of the rain barrel, and the ease of having water available to water our plants without the need to lug a heavy garden hose all over the yard. The only downers are the unavailability to locally purchase rain barrels and diverters and the cost. The cost though is a one time occurrence and with proper maintenance and winter storage the barrels should last for a long time.