Here is a handy tool that helps you collect rainwater to take care of your lawn. The Oatey Mystic Rainwater Collection System has a two-piece UV-resistance PVC construction. It works with most standard downspouts. It diverts water into a container or directly into your garden.
The Mystic can be installed into 2 x 3″ downspouts. It uses a 4ft hose to redirect water.