Rain barrels can be linked together to collect even more rainwater. To do so, place the barrels side by side. The first barrel that is collecting the water will have a plug in the upper port on one side. The side next to the second barrel will have the overflow elbow. Barrel number two will have an elbow in each port. Use a short piece of 3/4ID flex tube or hose to connect the two elbows. Once the barrel is full, the water will flow to the second barrel. Many barrels can be linked together. The first barrel should be plugged on one side and the last barrel should have and open overflow valve. For more information on connecting rain barrels please visit our youtube videos at https://www.youtube.com/results?search_query=the+great+american+rain+barrel+company