Here's another commonsense green lesson to take away from our grandparents' time. Rain is free. We pay for water. Why not collect free rainwater and slash the water bill? A rain barrel will save most homeowners about 1,300 gallons of water during the peak summer months. Also, diverting water from storm drains can alleviate stressed water systems and conserve limited resources, especially if you live in an arid climate. For an easy primer on rain barrels and how to make your own, check this out.