Collecting rainwater for use during dry months is an ancient practice that has never lost its value. Today, simple water collection systems made from recycled food barrels can mean a free source of non-potable water for plants, gardens, bird baths, and many other uses. Rainwater is ideal for all plants because it doesn’t contain dissolved minerals or added chemicals. One inch of rain falling on a 1,000 square foot roof yields approximately 600 gallons of water.