Rain water harvesting is collecting and storing rainwater for re-use on site, rather than allowing it to run off. Harvested water can be used for gardens, livestock, irrigation, and can even be used for drinking with proper treatment. Typically in the United States we use harvested water for irrigation.
With many areas of the country suffering from extreme drought it is important we utilize our water resources accordingly. For those of you just learning about this I’ll break it down simply. There are three basic ways to harvest rainwater in a residential setting.
1. Rain barrel: a tank used to collect and store harvested rain, typically from rooftops. These most often use gravity to create the pressure needed to move the water to the garden. They can range in size from 55 gallons to 500 gallons.
2. Underground cistern: a tank buried underground used to collect and store harvested rain. These cisterns typically require an electric pump to create the pressure needed to move the water to the end location. The type shown below, called the Rain xchange uses crates and a pond liner to create an underground storage area.
3. Surface drainage: An at grade drainage channel used to direct the water to the end location. These systems simply direct and disperse the water on the surface of the ground. The water is immediately distributed into the garden at the time of the storm event. These can be as small or big as necessary depending on the quantity of water coming off the roof. They should be lined with a rock material at least 3” size or greater to prevent erosion.
We’ll go into how to create these rain water systems in the following weeks but until then the first step is to find out how much water you will have coming off your roof. I like to use the rainwater harvesting online calculator to help me out with this.
For a look at my rain barrel and how I use it check out this video.