Rake the area under the trough so that you can remove the containers easily. Insert the PVC pipe, and add metal menders if you like to ensure the container's slit stays level with the trough. When it rains, the water will be directed from the trough, into the PVC pipe and then into your container. When the container is full, lift the PVC pipe out of the mouth of the container, remove the container, and water your plants. When the container is empty, put it back under the trough and slip the PVC pipe back down into the mouth of the container. If you like, you can purchase a rain barrel with which to pour the full containers.