HURRY Which textual evidence best supports this message? You can use water from your rain barrel for a lot of different things around the home and garden. So not only is the rain barrel water free, but it’s also free of chlorine and minerals. One of the benefits of a rain barrel is it holds that first bit of rain that’s coming off the roof or your driveway and prevents it from running into streams and causing erosion from high flows of water. I use it to fill my fish tank, even to wash the car if you want to. A rain barrel is a small investment for big dollar and environmental benefits.